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Passive house analysis in terms of energy performance
Accepted Manuscript Title: Passive House Analysis in Terms of Energy Performance Authors: Mirela Mihai, Vladimir Tanasiev, Cristian Dinca, Adrian Badea, Ruxandra Vidu PII: DOI: Reference:
S0378-7788(17)30829-0 http://dx.doi.org/doi:10.1016/j.enbuild.2017.03.025 ENB 7450
To appear in:
ENB
Received date: Revised date: Accepted date:
8-2-2016 7-2-2017 9-3-2017
Please cite this article as: Mirela Mihai, Vladimir Tanasiev, Cristian Dinca, Adrian Badea, Ruxandra Vidu, Passive House Analysis in Terms of Energy Performance, Energy and Buildings http://dx.doi.org/10.1016/j.enbuild.2017.03.025 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Passive House Analysis in Terms of Energy Performance
Mirela Mihai a, Vladimir Tanasiev a, Cristian Dinca a, Adrian Badea a,b and Ruxandra Vidu c,d,* a
Department of Energy Production and Use, University Politehnica of Bucharest 060042, Romania. b The Romanian Academy of Scientists, Bucharest 050094, Romania. c University of California, Davis, Department of Chemical Engineering and Materials Science, Davis CA 95616, United States of America. d The American Romanian Academy of Arts and Sciences, California, USA
*Corresponding author. E-mail address: [email protected]
GRAPHICAL ABSTRACT
Highlights
Low energy system implemented for a Passive House located in a zone with a temperate climate. The system combines EAHX (the earth-air heat exchange) technology with photovoltaic panels (PV). Study of the PV system in terms of energy production and economic investment. Analysis of the passive house in terms of energy performance through dynamic simulation in EnergyPlus software. The house has a good thermal comfort with minimum energy consumption close to 13 kWh/m2∙year.
Abstract: Passive Houses are buildings with low energy demand for heating (below 15 kWh/m2∙year), but provide comfortable indoor conditions. This paper presents the performance of an energy system designed for such a house located in Bucharest. Building system combines the earth-air heat exchange (EAHX) technology with photovoltaic panels. The photovoltaic panels were analyzed in terms of energy production and economic investment. The energy demand of the house was simulated using the EnergyPlus software in order to understand the house performance during cold and hot seasons using various occupancy scenarios. The results showed that the energy demand for a passive house is 14 kWh/m2∙year. Finally, the actual data measurement indicated that the passive house, has a good thermal comfort with a minimum energy consumption close to 13 kWh/m2∙year. The electricity generated from PV system during one year was 1556.5 kWh/year, the rest of necessary energy for consumption being supplied by the grid. Keywords: passive house, low energy building, dynamic simulation and energy efficiency. 1. Introduction In recent years, the global temperature has increased, due to the increase of CO2 concentration in atmosphere, which was generally caused by the increase in greenhouse gas emission (GES). In Europe, buildings are responsible for the most part of GES due to the fact that they use 40% of the primary energy [1]. About 85% of the energy consumed in buildings is used for heating, lighting and heating the domestic hot water. The majority of this energy could be saved by increasing the insulation of the building and by using efficient systems for heating or cooling [2, 3]. A solution to sustainable buildings is to integrate renewable energy systems, such as photovoltaic panels to produce electricity and solar thermal panels to heat domestic water [4]. European Union has decided that by year 2020, the energy consumption in buildings has to be reduced with 20% and GES with up to 20% [1, 5]. The passive house developed into the preferred concept for architects and researches in many countries (i.e. Germany, Switzerland, Austria and Central Europe), since it showed a high thermal comfort and a low energy consumption [6]. A Passive House is a building that has a comfortable indoor temperature during winter or summer, with a low energy request for heating or cooling of the space [6, 7]. The concept of Passive House was used for the first time in Darmstadt, Germany, and refers to a house with the following characteristics [8-11]:
annual space heat requirement of 15 kWh/(m2∙year); total energy consumption for heating, hot water and electricity should not exceed 120 kWh/(m2∙year);
leaked air volume must not be higher than 0.6 of the house volume per hour (𝑛50 ≤ 0.6ℎ−1 ) as measured at a pressure of 50 Pa.
The Passive House concept is based on reducing the heat losses [12]. This is achieved by i) a high thermal insulation and a raised thermal capacity of the envelope, which would keep the energy inside, ii) passive solar gains, and iii) an efficient heat recovery system [13]. In the world, there are various sustainable buildings having standard design that are used to evaluate the energy efficiency in buildings, such as BREEAM (UK), LEED (USA), Passive House (Germany) [4]. The BREEAM means the Building Research Establishment Environmental Assessment Method and represent the world’s leading sustainability assessment method for master planning project, infrastructure and buildings. BREEAM represent the measurement values of all categories in buildings from energy to the ecology [14]. The most certifying buildings is in the UK and other 50 countries around the world is made by BREEAM. The LEED means the Leadership in Energy and Environmental Design that evaluate the buildings, in terms of systems, design construction, operation, maintenance of homes and neighborhoods which help the owners to have a performance and sustainable house [15]. Passive House means an efficient building in terms of energy, with a temperature comfortable for the owners of the building at affordable [16]. Schnieders et al. [6] analyzed the energy consumption of the space heating in many Passive Houses that were built in five European countries under a program named the European CEPHEUS project. The results of the study on Passive Houses concepts were found reasonable for the occupants due to the fact that these buildings have low energy consumption and the temperature remained at an optimum level. These excellent results have demonstrated that the concepts of passive house may be implemented in the new residential houses [6]. Persson et al. [17] used a conventional software named DEROB-LTH for buildings and environment to study the case of a passive house in Sweden and to evaluate the feasibility of new technologies in building integration (such as windows, wall, HVAC, etc.). According to their results, it was estimated that the windows facing south have the best orientation from the energy point of view. This is because the solar gains through windows contribute to the space heating, to keep the minimum and the maximum indoor temperature at 23°C and 26°C, respectively [17]. Audenaert et al.[18] have analyzed the economic aspect of investment for the passive house concept in comparison with low energy buildings, taking into calculation the energy cost. In their study, a total of 11 building were analyzed, which were standard buildings, low energy buildings and passive houses. The results have shown that if the annual energy price increases by 10%, the return of investment for a passive house is 18 years [18]. If the annual energy price increases by 15%, then the passive house will be very profitable in terms of investment [18]. The investment is high for buildings such as passive houses because of the improved insulation and the ventilation system, which represent an additional cost compared to low-energy buildings or standard buildings [18, 19]. Dan et al. [20] have studied how the indoor parameters affect the energy consumption. In addition, they analyzed the life-cycle cost for a passive house located in University Politehnica Timisoara, Romania. The scope of their study was to demonstrate that applying the passive house concepts in Romania, might be an efficient solution for the new, more efficient, buildings. To conduct the studies, the group monitored the energy consumption, indoor temperature, CO2 level and humidity for a period of two years (2013 to 2015). The results showed that the indoor temperature in winter period has a value between 20°C and 22°C. Unlike winter season, the indoor temperature in summer was higher than outside,
because the house didn’t have any cooling system or architectural shades. For cooling the building, the researchers opened in the windows during the night. The energy consumption for heating was between 12 and 14 kWh/m2∙year. From the monitoring data result that the total primary energy requirement is less than 120 kWh/m2∙year. Dan et.al [20] calculated the energy demand and life-cycle cost of building relying on two programs: Passive House Planning Package software (H1) and DOSET software (H2) to evaluate the performance of building. The life-cycle cost was calculated by taking in consideration the initial investment cost, energy cost, and maintenance costs. The results of the investment with (H1) was estimated at 92.600 € and the result from (H2) was assessed at 73.000 €. The difference of the results of investment consist in: windows, thermal system, mechanical systems and building equipment. The result of pay-back of the investment for (H1) is 13 years and for (H2) the recovery is much faster [20]. I. Udrea et al. [21] studied the thermal comfort in summer period for an office building that was built as a passive house in Romania. They monitored the indoor temperature at all floors of the building, during two days between July 9 and July 11, 2013, and the results were analyzed by taking into consideration the results of the questionnaires distributed to the occupants to estimate the thermal comfort. In addition, the results were evaluated with standard EN15251 of thermal comfort. The temperature was measured with ComfortSense. In the second part of the study, the temperature was based on IAQ-CalcTM Indoor Air Quality Meter 7545, which is a professional instrument for investigating, monitoring indoor air quality (IAQ). The duration of measurements with ComfortSense was 3 minutes with a shorter step of discretization 2.5 seconds and was measured in 56 places of the building. To better understand the thermal comfort, 124 people were questioned for 16 days (from July 9 to August 19, 2013). A comparison between the two studies has shown that results are similar for the first floor of the building, which showed a perfect equilibrium between warm and cool temperatures. At the second floor the thermal comfort was not attained, the occupant complained of thermal discomfort (i.e. warm zone). In addition with the data measurement and the results of questioners, Udrea et al. [21] calculated the indoor temperature building based on EN15251 to obtain daily average indoor temperature, using mechanical cooling system and without HVAC. The results were the following: without HVAC, the indoor temperature was between values 20.74 °C to 32.7 °C, while using HVAC, the indoor temperature was between 19.75 °C and 27.75 °C. In conclusion the comfortable temperatures for this building study, were between values 22.1 °C and 28.7 °C. The results of this model building can be readily adapted to new office buildings. Badescu et al. [22] studied the same building as Udrea et al. [21] in terms of overheating using the Passive House Planning Package (PHPP) program. The PHPP program is based on the heating energy balance, heat distribution and supply, electricity demand and primary energy demand. In their study, a sensitivity analysis of the buildings was performed with PHPP to better understand the dependence of the cooling load on the thickness of the various layers constituting the envelopes. To have a good comparison various building situations the following cases have been considered:1) standard building that has a yearly heating requirement of 90.6 kWh/(m2∙year); 2) low energy building; 3) passive house as in [22]. The results of this study showed that the yearly overheating rates as function of walls thickness was as follows [22]:10% (building 1), 21% (building 2), and 31% (passive building, 3). The influence of internal heat source (IHS) on the cooling load and the indoor temperature has also been studies due to their influence on overheating rates and cooling loads. The maximum indoor temperature recorded were: 22 °C (building 1), 25 °C (building 2), and 27 °C (passive building, 3). These results obtained for a passive house building office showed that the office has to use the cooling system from June to August, with a high demand for cooling during
July. The maximum temperature in office in July was 29 °C but in living room, the maximum temperature did not exceed 25.5 °C [22]. From the results reported in this article we can figure out that in the future, there is a good idea to implement a passive house in Romania, but with a good ventilation system for cooling the space in the warm days. This paper is focused on the performance of the building in terms of energy demand for a passive house simulated using EnergyPlus software. The simulation results were compared with the actual energy consumption recorded for a passive house in Bucharest, Romania. To perform this simulation, the house was first characterized in terms of building architecture and building zone using the Google SketchUp software. Then, the EnergyPlus software was used to add thermal properties for each building element and weather conditions. 2. Case study and method 2.1. Description of the house 2.1.1. Building characteristics Envelope of the UPB Passive House was designed for a detailed study of the facade details, which may contribute to the relationship between cooling and heating of the house in correlation with the indoor temperature. Design of the passive house was analyzed with EnergyPlus and is presented in Figure 1. The UPB passive house is a duplex that has SouthEast orientation with different systems for heating and cooling. This study has been performed on the East Passive House. The house has two floors. The first floor is composed of a hall, technical room, living room, kitchen, bathroom and stairs (Figure 2.a), the second floor is composed of two bedrooms, two bathrooms, one office and one hall (Figure 2.b). The heat transmission properties of each element of envelope (i.e. wall, window, door, etc.) are listed in Table 1, which are very important parameters to determine the energy consumption for a house.
2.1.2. Building systems description The system used in the East Passive House for heating and cooling includes the earth to air heat exchanger (EAHX), a ventilation system air-to-air, mechanical ventilation heat recovery unit (MVHR) and an electrical resistance heat as illustrated in Figure 3. The EAHX is actually a pipeline that has 38 meters in length and is buried at 2.5 meters deep. The air that enters in the house is cooled or heated depending on the season, using the temperature of the ground. This pipeline contains inside silver particles for antimicrobial effect [23]. Also the pipeline has a thermal conductivity of 0.28 W/m/K for an efficient heat transfer between the air and the ground [23]. After crossing through the EAHX, the fresh air enters in the MVHR that is designed to recover the heat from the air in the house, which has a higher concentration of CO2, and use that heat to preheat the fresh air. MVHR has 93% efficiency for heat recovery. When the temperature in the house is not comfortable, an electrical resistance with a nominal power of 2.4 kW can be used to heat the air. The air with a high concentration of CO2 from bathrooms, hall and kitchen is evacuated from the building through sockets placed at the entrance of the building. Besides of this system for heating, the East Passive House has also photovoltaic panels that are installed on the roof of the house (this system is detailed in section 4). Also, there is a solar collector used for domestic hot water that is connected to a 200 L tank equipped with an electrical resistance. 2.2. Simulation tools
Various simulation programs are presently used to study and predict the energy consumption for Passive Houses or any other buildings. EnergyPlus 8.1 and Open Studio Plug-in for the Google SketchUp program allow for analyzing the buildings in terms of energy [25]. The analysis is based on the physical description of the building, the system for heating or cooling, and inside thermal comfort. EnergyPlus uses the IDF and EPW input files. These files are basically software interface, which introduce data about building architecture and weather. The IDF files contains technical data about the building envelope materials, HVAC system, hourly energy consumption divided in the multi-zone of building, etc., while the EPW files contains meteorological data of the Meteonorm 7.1.6 program [25]. This program is used by engineers, scientists and architects to design more energy efficient buildings. 2.2.1. Climate conditions analysis for the simulation Climate conditions analysis is an important guide for energy system design and integration because the energy consumption depends on the outside temperature. The weather conditions for Bucharest were analyzed in respect to solar radiation and ambient temperature. Figure 4 illustrates the monthly distribution of global radiation and diffuse radiation for Bucharest, as simulated by Meteonorm [26]. It is observed that the total solar radiation is usually high starting with March until August. Annual total solar radiation in Bucharest is 1413 kWh/m2/year. Figure 5, shows daily temperature distribution for Bucharest [26], the minimum and maximum values of monthly temperature distribution. The annual highest temperature is 35 °C in July and the lowest temperature is -15 °C in January.
2.3. Analysis of the performance of the building through simulation The energy performance of a building becomes efficient only when the occupants of the buildings feel thermal comfort. According to the ANSI/ASHRAE standard 55-2004, thermal comfort is defined as “a condition of mind which expresses a satisfaction with the thermal environment” and is rated by the people who occupy the building [27]. So, we can only assume that the thermal comfort depends on factors such as air-temperature, humidity and air ventilation, all of these factors depending on the perception of each person. Therefore, to reach a thermal comfort in the building, it is necessary to have a balance of energy consumption for heating or cooling in correlation to the indoor temperature, humidity level and ventilation ratio. To have a meaningful estimation of the energy demand required by a passive house, we must first take into account the schedule of occupancy. Daily occupancy profile of the house was set in this analysis for two people. In this scenario, a thermal comfort is assumed when users were present in the house, and a reduced energy consumption for heating with 50% when the occupancy was zero. Simulation was performed for a period of one year using a time step of 1 h. The occupancy of the entire building is 1 for two people and 0.5 when there is only one person in the house. Between 9:00 AM and 5:00 PM, the house is not occupied, so that the energy consumed during this period of time is minimal (Figure 6). House heating starts in October and continues up to March (i.e. for 6 months). The energy demand for heating was estimated by taking into consideration the U-value and the envelope thickness. Additionally, Figure 7 presents the energy demand for energy consumption in correlation with the outside temperature and the solar radiation for the East Passive House. The total energy demand for heating in this simulation is 1978.62 kWh/year (Figure 7) for the entire building surface of 140 m2, which means an energy demand of 14.1 kWh/m2∙ year [28].
The energy demand is as low as 14.1 kWh/m2∙year due to the robust insulation of the house. In order to better understand the energy demands for such a house, Table 2 illustrates the energy demand for each area separately for the passive house simulated. The energy demand is in relation with the surface of the rooms, occupancy profile of the house with outside temperature and indoor temperature. The indoor temperature is taken between 20 °C and 26 °C. This passive house has high thermal inertia that preserves inside the house a temperature comfortable for occupants, with further reduces the energy for heating. A significant aspect in reducing energy consumption during winter is given by solar gains through the south facade of the house because of the large windows that allow solar radiation to enter the house. Figure 8 shows the heating power demand in relationship to the solar gain and the inside temperature for the living room during a day in January. The 3 rd day of January was random chosen for simulation purposes as a day of the winter season. Additionally, it can be seen from Figure 8 that the energy consumption for heating the living room increases slightly during the night, which is required to maintain a constant temperature of 20 °C in the room, but then, the energy consumption, drops to zero during the day from 13:00 to 18:00 PM. In the simulation, there are solar gains from 08:00 AM to 17:00 PM, which minimizes the energy demand for heating. During the night, the indoor temperature is constant and does not exceed 20 °C. During the day between 12:00 and 17:00 PM, the temperature increases to 22 °Cdue to the solar gains especially in the rooms with a south orientation such as bedroom, living and south bathroom.
In Figure 9, the results of the simulation of the indoor temperature on the 3rd of January are presented. During the night, the indoor temperature is constant and does not exceed 20 °C, but during the day, the temperature increases to 22 °C, especially in the rooms with a south orientation such as bedroom, living and south bathroom, because of the solar gains. The temperature in the other rooms remains constant during the day. 3. Actual data measurement results 3.1. Management data and interior comfort The building has a computerized system that uses the Smart Building Controller (SBC) software [28], which manage the building to ensure a pleasant environment for occupants with a minimal energy consumption. The SBC uses data from sensors placed in the rooms (see Figure 2 for sensor placements), to control all the devices installed in the building [28]. The sensors measure the following room parameters: the indoor temperature, CO2 concentration, humidity, luminosity [29]. Solar radiation and outside temperature are also measured with pyrometers and sensors placed on the roof. The occupants of the Passive House are PhD students who carry out activities related to their doctoral research from 9:00 AM to 18:00 PM. The measurements were taken four times per hour for 24 hours, following the schedule: 00:00; 00:10; 00:30; 00:40 every day. The monitoring of passive house started in 2013 [29]. The case study for these data analysis was performed only for the winter season (from October 2014 to March 2015, which represents 6 months). We were interested to understand how much energy is consumed by heating, ventilation, lighting and electrical appliances.
During daytime, the room temperature ranges between 20 °C and 23 °C, which represent a comfortable temperature for the occupants. Other important parameters that dictate the level of comfort for occupants is represented by CO2 concentration and humidity levels in the room, especially in office buildings or institutional buildings (i.e. schools and universities), where there are many people occupying a room at a given time. When the humidity is too low, people who live in the building may experience discomfort because of the dry air. Moreover, the humidity depends on the ventilation system that introduces fresh air in living spaces. Additionally, if fresh air is often circulated in the rooms, the humidity level increases. The Passivhaus Institut (PHI) specifies that when the fresh air is heated at a temperature of 20 °C, the humidity in the air decreases to 17.6% [30]. Figure 10 shows that the humidity measured in the house is within normal levels, having values between 17% and 27% at a temperature between 20 °C and 23 °C, which are typical values for winter period. The normal humidity level for a building varies between 30-70%, but differs from one building to another, depending on the type of building. Regarding the CO2 concentration in a given room, air quality inside the building depends on the rate of ventilation that introduces fresh air into the house. It is essential to monitor indoor air quality (IAQ) for health, comfort and productivity purposes. According to ASHRAE standard 62-2001, the ventilation rate depends on the floor area, which means that the air exchange per hour should be for residential buildings about 0.35 ACH but not less 15 cfm (cubic feet per minute) or about 7.5 L/s per person [31]. The admissible value of CO2 concentration in a habitable space should not exceed 800 ppm above outdoor air levels. For a house with sedentary occupancy, the CO2 concentration level may easily increase up to 1100 ppm. The CO2 concentration in buildings (such as schools, office buildings) is between 400 ppm and 1500 ppm, depending on the surface of the building [32]. In our case, we have measured in a typical day of winter a concentration of CO2 between 650 ppm and 667 ppm (Figure 10), which represents a normal value at a ventilation flow rate of 80 m3/h.
3.2. The energy consumption A detailed analysis of the energy consumed by the passive house was performed for the winter period which lasted for six months (i.e. from October to March). Table 3 shows that the heating system consumes most of the energy, followed by the electronics used in the living room, where the occupants spent most of the time. Another large portion of the energy consumed by the house is represented by the monitoring system that uses 558.35 kWh. The total energy consumption for heating in passive house was 1838.02 kWh/year; if this value is divided to the surface of the house, i.e. 140 m2, an energy consumption of about 13.12 kWh/m2∙year is obtained. October and November represent the lowest energy consumption for heating. The heating system was turned on during the last six days of October when the outside temperature dropped to 0 °C, thus maintaining an indoor temperature above 20 °C. To understand how much energy is consumed for heating to maintain a temperature that is comfortable, the results for two winter months in December and March are presented (Figure 11-12). December and January were the coldest months of the year, when the outside temperature dropped to -15 °C. For this reason, the energy consumption in December was as high as 425.12 kWh (3.03 kWh/m2) while the average inside temperature was kept at value of 20 °C as shown in Figure 11.
Figure 12 presents the energy consumption required for heating during March. The average indoor temperature was maintained at 23°C, although the outside average temperature fell to 0 °C in some days of March. From this analysis, it was observed that the energy consumption every day during the two months was between 10 kWh/day to 15 kWh/day. 3.3. Renewable electricity systems Due to the fact the energy consumption in buildings increased in the past years, there is a continuous pursuit for integrating photovoltaic panels on the facades and roofs of buildings. Electricity from photovoltaic panels is a clean energy, environmentally friendly and sustainable source [33]. For this reason, photovoltaic panels are ideal solutions for commercial building and residential houses. In this study, the passive house has, besides a heating system, a renewable energy source provided by photovoltaic panels installed on the roof of the house. These solar panels are made of polycrystalline Si having an output power of about 3 kW. The renewable system is connected to the local grid of University Politehnica of Bucharest and has the following specification presented in Table 4. PV modules are connected to an inverter that transforms the direct current (DC) to alternative current (AC), and a distribution board connected to the grid to export and import energy. An investigation of the PV system performance of energy delivered over one year was performed from September 15, 2014 to September 15, 2015 (Figure 13). The total energy supplied by the PV system over one year was 1556.5 kWh/year, and the rest of the required energy consumed being delivered by the grid. The maximum energy produced by the PV system was recorded in June, i.e. 229.4 kWh/month and the minimum energy delivered by PV was recorded in November, i.e. 19.50 kWh/month. The low electricity production recorded in November was due to the fact that November was the rainiest month of the year, and the intensity of solar radiation was very low. The daily average energy produced by PV in November was estimated to be about 0.92 kWh/day.
3.3.1 Economic investment calculation An economic investment for the PV system was performed with a simulation program named System Advisor Model (SAM). This software can be used to predict the energy production, but also may calculate the investment cost of a PV system connected to grid. SAM was developed by the National Renewable Energy Laboratory (NREL) for engineering and research. To perform this simulation, parameters such as PV system type, climate data and location must be run taking into account the price of energy delivered to the grid. In this simulation, the economic analysis of the cost of the investment was performed taking into account the following input data: i) the price of photovoltaic panels was 8831€, ii) the price for a single panel was 663€, iii) the cost of invertor was 1262€. The total investment cost was 12197€ (considering the price of photovoltaics panels, inverter and installation cost i.e. Figure 14). To find out the payback of the investment cost, the following economic parameters were considered: i) the sale price of the energy produced: 0.26 euro cents for 1 kWh, and ii) the state subsidy: 50% of the total investment. Figure 15 shows that, in the first year energy production (blue line), 50% of the total cost is recovered from the state. The return of investment turns positive starting with the 9th year of PV system operation. The investment is recovered from the surplus energy produced by the PV system, and the unused electricity is injected into the grid. The price of photovoltaic on the economic market varies from one day to another. Therefore, the investment may turn positive much faster when the PV system cost
is reduced by more than 50%. For this PV system, the total electricity production was 2307.1 kWh during one year (Figure 16). In the winter months, the electricity provided by the PV system is half compared to the summer months, due to the fact that the solar radiation is diffused in winter and weather conditions are bad.
The electricity production of the PV system is the highest from April to August as shown by both measured and simulation data. In addition, the actual data measured for energy production was 1556.5 kWh/year during one year, compared to the energy production of 2307.1 kWh obtain by simulation. This difference can be explained by the fact that the PV system is assumed in simulation to operate in ideal conditions.
4. Discussion The purpose of this study was to analyze the energy consumption and production of a passive house in Romania by comparing the actual performance with simulation data for similar conditions. Simulation of the energy consumptions for a real house is very important to understand the actual energy consumption and generation, and where are the largest differences. Based on the occupancy schedule, the simulated demand of energy for heating was 14.1 kWh/m2∙year, while the actual energy consumption was 13.12 kWh/m2∙year. The energy demand for space heating is low in winter due to the solar gains promoted by both south orientation of the house and large windows. Simulation results showed that the temperature increased by two degrees in the rooms with south orientation such as living room, office, south bedroom and south bathroom. Beside energy performance, other parameters such as indoor temperature, CO2 and humidity levels are critically important for a Passive House analysis. The actual measurements of humidity and CO2 concentration showed that their values are within the normal range for the Passive House. In addition, the indoor temperature during the day was comfortably kept between 20 °C and 22 °C during the winter season. The electricity generated from PV system during one year was 1556.5 kWh/ year, the rest of the necessary energy for consumption being supplied by the grid. The economics of PV system integration were analyzed by calculating the return of investment. Because the initial investment cost is high at the actual PV system prices, the return of investment turns positive only after 9 years. After the investment is recovered, the PV system becomes profitable. This study shows how a Passive House’s energy performance responds to new concepts such as those introduced in this study: heating or cooling system depending on the season, monitoring policy implemented in the energy management of the house and the use of renewable electricity sources. Besides this, a critical role is played by the reduction of the energy consumption of a house. This study shows that it is possible to have a pleasant thermal comfort maintained in the house at low energy consumption when customized isolation for a given location is used. This case study represents a practical model for the new houses that will be built in Romania. 5. Conclusions This paper presents a study of an efficient energy building, built in Romanian climat condition, according with the passive house standard. The building combines efficient
HVAC systems and integretes renewable energy system to generate electricity. We studied the evolution of the building and recorded the energy consumption during 6 months. The results show that the building has a low energy consumption mainly due to the SBC policy of the building. This study brings essential information that can be used in the future for all the buildings that will be built in Romania, because most of the buildings are residential and represent 80%of the buildings, with a large energy consumption for heating (i.e. 56% of the total energy consomption). Additionally, the law imposed by Eurpean Comision concerning that all the buildings should be nearly zero energy building (nZEB) by the year 2018, Romania is required to focus on the reduction of energy consumtion and emissions of greenhouse. In the future, this passive house can be a plus energy building, if doubls the number of photovoltaic panels installed or may be just a zero energy building. This pasive house represents a model of energy efficient building, sustainable and ecological, and represents a solution for the future residential houses. Acknowledgment The work has been funded by the Sectorial Operational Programmer Human Resources Development 2007-2013 of the Ministry of European Funds through the Financial Agreement POSDRU/159/1.5/S/132395. This passive house was built during a research project developed through a partnership between the University POLITEHNICA of Bucharest (UPB), Technical University of Civil Engineering Bucharest (UTCB), University of Architecture and Urbanism “ION MINCU” (UAIM), Institute for Studies and Power Engineering (ISPE), Academy of Romanian Scientists (AOSR), Electro-Technical Research Institute (ICPE) and a private company (AGECOM). Reference [1] Directive 2009/28/EC of the European Parliament and of the Council, Official Journal of the European Union (2009) http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0028.
[2] Badescu V, Simulation analysis for the active solar heating system of a passive house, Journal of Applied Thermal Engineering 25 (2005) 2754-63. [3] A. Buonomano, F.Calise, G. Ferruzzi, A. Palombo, Dynamic energy performance analysis: Case study for energy efficiency retrofits of hospital buildings, Journal of Energy 78 (2014) 555-72. [4] L. Wang, J. Gwilliam, P. Jones, Case study of zero energy house design in UK, Journal of Energy and Buildings 41 (2009) 1215–22. [5] Directive 2009/29/EC of the European Parliament and of the Council, Official Journal of the European Union (2009) http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0029.
[6] Jurgen Schniedersa, Andreas Hermelink. CEPHEUS results: measurements and occupants’ satisfaction provide evidence for Passive Houses being an option for sustainable building. Energy Policy. 34 (2006) 151-71. [7] V. Badescu , M. D. Staicovici, Renewable energy for passive house heating. Model of the active solar heating system, Journal of Energy and Buildings 38 (2006) 129–41. [8] IEEA, The passivhauss standard in european warm climates, EC funded project: Marketable Passive Homes for Winter and Summer Comfort (2007)
http://www.eerg.it/passiveon.org/CD/1.%20Technical%20Guidelines/Part%203/Part%203.pdf. [9] Wolfgang Feist, Certification criteria for residential Passive House buildings, Passive House Institute (2013) http://www.passiv.de/downloads/03_certification_criteria_residential_en.pdf. [10] G.E. Vlad, C. Ionescu, H. Necula, Simulation and Energy Efficiency Evaluation of a Low-Energy Building. Journal of Sustainable Energy III (June 2012). [11] J. Schnieders W. Feist, L. Rongen, Passive Houses for different climate zones, Journal of Energy and Buildings 105 (15 October 2015) 71–87. [12] W. Feist, J. Schnieders, V. Dorer, A. Haas, Re-inventing air heating: Convenient and comfortable within the frame of the Passive House concept, Journal of Energy and Buildings 37 (2005) 1186-203. [13] H.M. Taleb, Using passive cooling strategies to improve thermal performance and reduce energy consumption of residential buildings in U.A.E. buildings, Journal of Frontiers of Architectural Resarch 3 (2014) 154-65. [14] Building Research Establishment Environmental Assessment Method - BREEAM http://wwwbreeamcom.
[15] Ledership in Energy and Environmental Design - LEED http://wwwusgbcorg/leed.
[16]
Passive
house
-
Passivhaus
Institut
(PHI)
http://passivehousecom/02_informations/01_whatisapassivehouse/01_whatisapassivehousehtm.
[17] M.L. Persson, A. Roos, M. Wall, Influence of window size on the energy balance of low energy houses, Journal of Energy and Buildings 38 (2006) 181–8. [18] A. Audenaert, S.H. De Cleyn, B. Vankerckhove, Economic analysis of passive houses and low-energy houses compared with standard houses, Journal of Energy Policy 36 (2008) 47-55. [19] L. Georges, C.Massart, G.Van Moeseke , A.De Herde, Environmental and economic performance of heating systems for energy-efficent dwellings: Case of passive and lowenergy, Journal of Energy Policy 40 (2012) 452–64. [20] D. Dan, C. Tanasa, V. Stoian, S. Brata, D. Stoian, T. Nagy Gyorgy, S.C. Florut. Passive house design - An efficient solution for residential buildings in Romania. Energy for Sustainable Development 32 (2016) 99-109. [21] Ioana Udrea, Cristian Croitoru, Ilinca Nastase, Ruxandra Crutescu, Viorel Badescu. Thermal comfort in a Romanian Passive House. Preliminary results. Energy Procedia 85 (2016) 575-583. [22] Viorel Badescu, Nadine Laaser, Ruxandra Crutescu. Warm season cooling requirements for passive buildings in Southeastern Europe (Romania). Energy 35 (2010) 3284-3300. [23] G.E. Vlad, C. Ionescu, H. Necula, A. Badea , Simulation of an air heating/cooling system that uses the ground thermal potential and heat recovery, U.P.B. Sci. Bull. 75 (2013). [24] A. Badea T.Baracu, C. Dinca, D. Tutica, A life-cycle cost analysis of the passive house “POLITEHNICA” from Bucharest, Journal of Energy and Buildings 80 (2014) 542-55. [25] Energy U.S. Department of Energy, EnergyPlus Energy Simulation Software (2015). http://apps1eereenergygov/buildings/energyplus/?utm_source=EnergyPlus&utm_medium=redirect &utm_campaign=EnergyPlus%2Bredirect%2B1.
[26] Meteonorm Software, offers you simple access to accurate data for any place on Earth: Irradiation, temperature and more weather parameters are available (2015) http://meteonorm.com.
[27] ASHRAE Standard 55-2004, Thermal Environmental Conditions for Human Occupancy (2004) http://wwwalmasesepahancom/fh/download/ASHRAE_Thermal_Comfort_Standardpdf. 2004.
[28] V. Tanasiev, H.Necula, S. Costinas, G. Sava, A. Badea, Achieving energy savings and thermal comfort through intermittent heating in very low energy buildings, International Conference on Environment and Electrical Engineering (2015) 2183 - 8. [29] M.B. Carutasiu, V.Tanasiev, C. Ionescu, A. Danu, H. Necula, A. Badea, Reducing energy consumption in low energy buildings through implementation of a policy system used in automated heating systems, Journal of Energy and Buildings 94 (2015) 227-39. [30] Passiv House Institute, Ventilation and Humidity - Their conection explained (2007) http://www.passivhaustagung.de/Passive_House_E/ventilation_and_humidity.htm.
[31] ASHRAE Standard 62-2001, Ventilation for Acceptable Indoor Air Quality (2001). [32] Ashrae handbook committeeFundamentals (2001) http://systemssolution.net/cadtechno/0%20SAMPLE/SPECs%20&%20DETAILS/BOOKS%20MECHANI CAL/HVAC/ASHRAE%20HVAC%202001%20Fundamentals%20Handbook.pdf.
[33] M.I. Mihai, V.Tanasiev, A. Badea and R. Vidu. The influence of climatic factors on the performance of photovoltaic panels. ARA Proceedings. 39 (2015) 70. http://dx.doi.org/10.14510/39ARA2015.3915
Figure 1. The Passive house from UPB campus, simulated in EnergyPlus.
Figure 2. Building plan: ground floor (a) and second floor (b). Sensor placement and distribution are also shown in blue in the floor plans
Figure 3. Building systems of the East Passive House UPB, Ro [24]. 1) Solar collector; 2) cold water pipe; 3) hot water tank; 4) domestic hot water outlet, 5) electric resistance heat; 6) MVHR; 7) EAHX by-pass; 8) condensate drain well, 9) EAHX, 10) electric radiant panel.
Figure 4. Monthly solar radiation distribution for Bucharest, Romania.
Figure 5. Daily temperature Bucharest, Romania.
distribution
Figure 6. Hourly occupancy profiles of the passive house.
Figure 7. Energy demand simulated for heating according to outside temperature and solar radiation.
for
Figure 8. The simulated energy consumption for the living room on the 3 rd January.
Temperature [°C]
22.5 22
South bedroom Living room
21.5 21 20.5
20 1
3
5
7
9
11 13 15 Time (hours)
17
19
21
23
Figure 9. Building simulated indoor temperature for each room on the 3rd of January (Note: the temperature for the following rooms was 20 oC: North bedroom, north bathroom, north deposit, technic room, and vestibule.
Figure 10. The CO2 concentration and humidity, during the 2nd of January, 2015.
Figure 11. Energy consumption for heating in December of 2014.
Figure 12. Energy consumption for heating in March of 2015.
Figure 13. The energy production 2014-2015.
Figure 14. Investment cost of the PV system. 20,000 15,000
EURO (€)
10,000 5,000 0 -5,000 Cumulative payback - expenses excluded (€)
-10,000
Investment recovery (€)
-15,000 -20,000 1
3
5
7
9
11
13
15
PERIOD (YEARS)
Figure 15. Payback time of the investment cost
17
19
21
23
25
Figure 16. The energy production of PV system in the simulation
Tabel 1. The U-values and thickness of each construction elements. Component buildings
of
Exterior Wall
Roof
Ground floor
Party wall Neighbor
Windows Door
to
Elements construction
of
Thickness [mm]
Interior plaster 22 Cellular concrete Ytong 250 Mineral wool 300 U-value 0.122 [W/(m2∙K)] Plaster 22 Reinforced concrete 130 Mineral wool 400 U-value 0.107 [W/(m2∙K)] Parquet 22 OSB board 8 Lightly reinforced 50 EPS high density 150 Reinforced concrete 120 XPS polystyrene 180 Lightly reinforced 50 U-value 0.114 [W/(m2∙K)] Plaster 22 Solid brick 250 Plaster 22 U-value 1.594 [W/(m2∙K)] Component G-value [W/m2∙K] Low-E Saint Gobain Glass 0.5 REHAU frame REHAU door -
U-value λ [W/(m∙K)] 0.800 0.270 0.040 0.800 1.740 0.040 0,200 0.130 1.100 0.040 1.740 0.040 1.100 0.8 0.8 0.8 U-value [W/(m∙K)] 0.6 0.78 0.8
Tabel 2. Energy demand for East Passive House estimated using the same procedure as detailed previously [28]. Zone area
Area [m2]
Living room Technical room Hall North bathroom Deposit North bedroom Office South bedroom South bathroom Total [m2] Total [kWh/m2∙year]
70.4 5.16 16.2 6.75 4.39 12.6 12.43 17.64 8.64 140 14.1
Windows surface [m2] 15.27 0 0 1.01 1.01 1.64 2.34 4.38 1.01
Energy demand for heating [kWh/year] 1103.17 52.17 90.26 67.26 102.33 203.77 121.67 156.99 62.97
Tabel 3. Energy consumption (kWh) measured in the building during 6 months, (2014 - 2015, represents the winter period) Period
Electronic devices [kWh]
Lights
Appliances for kitchen [kWh]
Electrical resistance [kWh]
Ventilation
October
24.00
5.23
18.70
50.65
6.53
91.82
November
356.23
7.83
14.98
197.65
48.51
93.62
December
242.08
12.64
49.62
425.12
79.15
99.21
January
375.23
4.95
30.51
445.96
45.20
92.61
February
609.06
0
56.31
258.74
0
85.10
March
48.18
0
141
459.90
68.31
95.99
Months total consumption
1654.78
30.65
311.12
1838.02
247.7
558.35
(Months)
[kWh]
[kWh]
Monitoring system [kWh]
Tabel 4. The PV parameters specification and inverter: Parameters (photovoltaics)
Value
Parameters (Inverter)
Value
Rated power
230.7 W/PV
Nominal power
3.0 kW
Area
~ 22 m2
Operating voltage
120-580 V
Short circuit current
8.24 A
Number
1
Open circuit voltage
36.7 V
Frequency
50/60 Hz
Modules
13 PV
-
-
Total rated power
3 kW
-
-
S0378-7788(17)30829-0 http://dx.doi.org/doi:10.1016/j.enbuild.2017.03.025 ENB 7450
To appear in:
ENB
Received date: Revised date: Accepted date:
8-2-2016 7-2-2017 9-3-2017
Please cite this article as: Mirela Mihai, Vladimir Tanasiev, Cristian Dinca, Adrian Badea, Ruxandra Vidu, Passive House Analysis in Terms of Energy Performance, Energy and Buildings http://dx.doi.org/10.1016/j.enbuild.2017.03.025 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Passive House Analysis in Terms of Energy Performance
Mirela Mihai a, Vladimir Tanasiev a, Cristian Dinca a, Adrian Badea a,b and Ruxandra Vidu c,d,* a
Department of Energy Production and Use, University Politehnica of Bucharest 060042, Romania. b The Romanian Academy of Scientists, Bucharest 050094, Romania. c University of California, Davis, Department of Chemical Engineering and Materials Science, Davis CA 95616, United States of America. d The American Romanian Academy of Arts and Sciences, California, USA
*Corresponding author. E-mail address: [email protected]
GRAPHICAL ABSTRACT
Highlights
Low energy system implemented for a Passive House located in a zone with a temperate climate. The system combines EAHX (the earth-air heat exchange) technology with photovoltaic panels (PV). Study of the PV system in terms of energy production and economic investment. Analysis of the passive house in terms of energy performance through dynamic simulation in EnergyPlus software. The house has a good thermal comfort with minimum energy consumption close to 13 kWh/m2∙year.
Abstract: Passive Houses are buildings with low energy demand for heating (below 15 kWh/m2∙year), but provide comfortable indoor conditions. This paper presents the performance of an energy system designed for such a house located in Bucharest. Building system combines the earth-air heat exchange (EAHX) technology with photovoltaic panels. The photovoltaic panels were analyzed in terms of energy production and economic investment. The energy demand of the house was simulated using the EnergyPlus software in order to understand the house performance during cold and hot seasons using various occupancy scenarios. The results showed that the energy demand for a passive house is 14 kWh/m2∙year. Finally, the actual data measurement indicated that the passive house, has a good thermal comfort with a minimum energy consumption close to 13 kWh/m2∙year. The electricity generated from PV system during one year was 1556.5 kWh/year, the rest of necessary energy for consumption being supplied by the grid. Keywords: passive house, low energy building, dynamic simulation and energy efficiency. 1. Introduction In recent years, the global temperature has increased, due to the increase of CO2 concentration in atmosphere, which was generally caused by the increase in greenhouse gas emission (GES). In Europe, buildings are responsible for the most part of GES due to the fact that they use 40% of the primary energy [1]. About 85% of the energy consumed in buildings is used for heating, lighting and heating the domestic hot water. The majority of this energy could be saved by increasing the insulation of the building and by using efficient systems for heating or cooling [2, 3]. A solution to sustainable buildings is to integrate renewable energy systems, such as photovoltaic panels to produce electricity and solar thermal panels to heat domestic water [4]. European Union has decided that by year 2020, the energy consumption in buildings has to be reduced with 20% and GES with up to 20% [1, 5]. The passive house developed into the preferred concept for architects and researches in many countries (i.e. Germany, Switzerland, Austria and Central Europe), since it showed a high thermal comfort and a low energy consumption [6]. A Passive House is a building that has a comfortable indoor temperature during winter or summer, with a low energy request for heating or cooling of the space [6, 7]. The concept of Passive House was used for the first time in Darmstadt, Germany, and refers to a house with the following characteristics [8-11]:
annual space heat requirement of 15 kWh/(m2∙year); total energy consumption for heating, hot water and electricity should not exceed 120 kWh/(m2∙year);
leaked air volume must not be higher than 0.6 of the house volume per hour (𝑛50 ≤ 0.6ℎ−1 ) as measured at a pressure of 50 Pa.
The Passive House concept is based on reducing the heat losses [12]. This is achieved by i) a high thermal insulation and a raised thermal capacity of the envelope, which would keep the energy inside, ii) passive solar gains, and iii) an efficient heat recovery system [13]. In the world, there are various sustainable buildings having standard design that are used to evaluate the energy efficiency in buildings, such as BREEAM (UK), LEED (USA), Passive House (Germany) [4]. The BREEAM means the Building Research Establishment Environmental Assessment Method and represent the world’s leading sustainability assessment method for master planning project, infrastructure and buildings. BREEAM represent the measurement values of all categories in buildings from energy to the ecology [14]. The most certifying buildings is in the UK and other 50 countries around the world is made by BREEAM. The LEED means the Leadership in Energy and Environmental Design that evaluate the buildings, in terms of systems, design construction, operation, maintenance of homes and neighborhoods which help the owners to have a performance and sustainable house [15]. Passive House means an efficient building in terms of energy, with a temperature comfortable for the owners of the building at affordable [16]. Schnieders et al. [6] analyzed the energy consumption of the space heating in many Passive Houses that were built in five European countries under a program named the European CEPHEUS project. The results of the study on Passive Houses concepts were found reasonable for the occupants due to the fact that these buildings have low energy consumption and the temperature remained at an optimum level. These excellent results have demonstrated that the concepts of passive house may be implemented in the new residential houses [6]. Persson et al. [17] used a conventional software named DEROB-LTH for buildings and environment to study the case of a passive house in Sweden and to evaluate the feasibility of new technologies in building integration (such as windows, wall, HVAC, etc.). According to their results, it was estimated that the windows facing south have the best orientation from the energy point of view. This is because the solar gains through windows contribute to the space heating, to keep the minimum and the maximum indoor temperature at 23°C and 26°C, respectively [17]. Audenaert et al.[18] have analyzed the economic aspect of investment for the passive house concept in comparison with low energy buildings, taking into calculation the energy cost. In their study, a total of 11 building were analyzed, which were standard buildings, low energy buildings and passive houses. The results have shown that if the annual energy price increases by 10%, the return of investment for a passive house is 18 years [18]. If the annual energy price increases by 15%, then the passive house will be very profitable in terms of investment [18]. The investment is high for buildings such as passive houses because of the improved insulation and the ventilation system, which represent an additional cost compared to low-energy buildings or standard buildings [18, 19]. Dan et al. [20] have studied how the indoor parameters affect the energy consumption. In addition, they analyzed the life-cycle cost for a passive house located in University Politehnica Timisoara, Romania. The scope of their study was to demonstrate that applying the passive house concepts in Romania, might be an efficient solution for the new, more efficient, buildings. To conduct the studies, the group monitored the energy consumption, indoor temperature, CO2 level and humidity for a period of two years (2013 to 2015). The results showed that the indoor temperature in winter period has a value between 20°C and 22°C. Unlike winter season, the indoor temperature in summer was higher than outside,
because the house didn’t have any cooling system or architectural shades. For cooling the building, the researchers opened in the windows during the night. The energy consumption for heating was between 12 and 14 kWh/m2∙year. From the monitoring data result that the total primary energy requirement is less than 120 kWh/m2∙year. Dan et.al [20] calculated the energy demand and life-cycle cost of building relying on two programs: Passive House Planning Package software (H1) and DOSET software (H2) to evaluate the performance of building. The life-cycle cost was calculated by taking in consideration the initial investment cost, energy cost, and maintenance costs. The results of the investment with (H1) was estimated at 92.600 € and the result from (H2) was assessed at 73.000 €. The difference of the results of investment consist in: windows, thermal system, mechanical systems and building equipment. The result of pay-back of the investment for (H1) is 13 years and for (H2) the recovery is much faster [20]. I. Udrea et al. [21] studied the thermal comfort in summer period for an office building that was built as a passive house in Romania. They monitored the indoor temperature at all floors of the building, during two days between July 9 and July 11, 2013, and the results were analyzed by taking into consideration the results of the questionnaires distributed to the occupants to estimate the thermal comfort. In addition, the results were evaluated with standard EN15251 of thermal comfort. The temperature was measured with ComfortSense. In the second part of the study, the temperature was based on IAQ-CalcTM Indoor Air Quality Meter 7545, which is a professional instrument for investigating, monitoring indoor air quality (IAQ). The duration of measurements with ComfortSense was 3 minutes with a shorter step of discretization 2.5 seconds and was measured in 56 places of the building. To better understand the thermal comfort, 124 people were questioned for 16 days (from July 9 to August 19, 2013). A comparison between the two studies has shown that results are similar for the first floor of the building, which showed a perfect equilibrium between warm and cool temperatures. At the second floor the thermal comfort was not attained, the occupant complained of thermal discomfort (i.e. warm zone). In addition with the data measurement and the results of questioners, Udrea et al. [21] calculated the indoor temperature building based on EN15251 to obtain daily average indoor temperature, using mechanical cooling system and without HVAC. The results were the following: without HVAC, the indoor temperature was between values 20.74 °C to 32.7 °C, while using HVAC, the indoor temperature was between 19.75 °C and 27.75 °C. In conclusion the comfortable temperatures for this building study, were between values 22.1 °C and 28.7 °C. The results of this model building can be readily adapted to new office buildings. Badescu et al. [22] studied the same building as Udrea et al. [21] in terms of overheating using the Passive House Planning Package (PHPP) program. The PHPP program is based on the heating energy balance, heat distribution and supply, electricity demand and primary energy demand. In their study, a sensitivity analysis of the buildings was performed with PHPP to better understand the dependence of the cooling load on the thickness of the various layers constituting the envelopes. To have a good comparison various building situations the following cases have been considered:1) standard building that has a yearly heating requirement of 90.6 kWh/(m2∙year); 2) low energy building; 3) passive house as in [22]. The results of this study showed that the yearly overheating rates as function of walls thickness was as follows [22]:10% (building 1), 21% (building 2), and 31% (passive building, 3). The influence of internal heat source (IHS) on the cooling load and the indoor temperature has also been studies due to their influence on overheating rates and cooling loads. The maximum indoor temperature recorded were: 22 °C (building 1), 25 °C (building 2), and 27 °C (passive building, 3). These results obtained for a passive house building office showed that the office has to use the cooling system from June to August, with a high demand for cooling during
July. The maximum temperature in office in July was 29 °C but in living room, the maximum temperature did not exceed 25.5 °C [22]. From the results reported in this article we can figure out that in the future, there is a good idea to implement a passive house in Romania, but with a good ventilation system for cooling the space in the warm days. This paper is focused on the performance of the building in terms of energy demand for a passive house simulated using EnergyPlus software. The simulation results were compared with the actual energy consumption recorded for a passive house in Bucharest, Romania. To perform this simulation, the house was first characterized in terms of building architecture and building zone using the Google SketchUp software. Then, the EnergyPlus software was used to add thermal properties for each building element and weather conditions. 2. Case study and method 2.1. Description of the house 2.1.1. Building characteristics Envelope of the UPB Passive House was designed for a detailed study of the facade details, which may contribute to the relationship between cooling and heating of the house in correlation with the indoor temperature. Design of the passive house was analyzed with EnergyPlus and is presented in Figure 1. The UPB passive house is a duplex that has SouthEast orientation with different systems for heating and cooling. This study has been performed on the East Passive House. The house has two floors. The first floor is composed of a hall, technical room, living room, kitchen, bathroom and stairs (Figure 2.a), the second floor is composed of two bedrooms, two bathrooms, one office and one hall (Figure 2.b). The heat transmission properties of each element of envelope (i.e. wall, window, door, etc.) are listed in Table 1, which are very important parameters to determine the energy consumption for a house.
2.1.2. Building systems description The system used in the East Passive House for heating and cooling includes the earth to air heat exchanger (EAHX), a ventilation system air-to-air, mechanical ventilation heat recovery unit (MVHR) and an electrical resistance heat as illustrated in Figure 3. The EAHX is actually a pipeline that has 38 meters in length and is buried at 2.5 meters deep. The air that enters in the house is cooled or heated depending on the season, using the temperature of the ground. This pipeline contains inside silver particles for antimicrobial effect [23]. Also the pipeline has a thermal conductivity of 0.28 W/m/K for an efficient heat transfer between the air and the ground [23]. After crossing through the EAHX, the fresh air enters in the MVHR that is designed to recover the heat from the air in the house, which has a higher concentration of CO2, and use that heat to preheat the fresh air. MVHR has 93% efficiency for heat recovery. When the temperature in the house is not comfortable, an electrical resistance with a nominal power of 2.4 kW can be used to heat the air. The air with a high concentration of CO2 from bathrooms, hall and kitchen is evacuated from the building through sockets placed at the entrance of the building. Besides of this system for heating, the East Passive House has also photovoltaic panels that are installed on the roof of the house (this system is detailed in section 4). Also, there is a solar collector used for domestic hot water that is connected to a 200 L tank equipped with an electrical resistance. 2.2. Simulation tools
Various simulation programs are presently used to study and predict the energy consumption for Passive Houses or any other buildings. EnergyPlus 8.1 and Open Studio Plug-in for the Google SketchUp program allow for analyzing the buildings in terms of energy [25]. The analysis is based on the physical description of the building, the system for heating or cooling, and inside thermal comfort. EnergyPlus uses the IDF and EPW input files. These files are basically software interface, which introduce data about building architecture and weather. The IDF files contains technical data about the building envelope materials, HVAC system, hourly energy consumption divided in the multi-zone of building, etc., while the EPW files contains meteorological data of the Meteonorm 7.1.6 program [25]. This program is used by engineers, scientists and architects to design more energy efficient buildings. 2.2.1. Climate conditions analysis for the simulation Climate conditions analysis is an important guide for energy system design and integration because the energy consumption depends on the outside temperature. The weather conditions for Bucharest were analyzed in respect to solar radiation and ambient temperature. Figure 4 illustrates the monthly distribution of global radiation and diffuse radiation for Bucharest, as simulated by Meteonorm [26]. It is observed that the total solar radiation is usually high starting with March until August. Annual total solar radiation in Bucharest is 1413 kWh/m2/year. Figure 5, shows daily temperature distribution for Bucharest [26], the minimum and maximum values of monthly temperature distribution. The annual highest temperature is 35 °C in July and the lowest temperature is -15 °C in January.
2.3. Analysis of the performance of the building through simulation The energy performance of a building becomes efficient only when the occupants of the buildings feel thermal comfort. According to the ANSI/ASHRAE standard 55-2004, thermal comfort is defined as “a condition of mind which expresses a satisfaction with the thermal environment” and is rated by the people who occupy the building [27]. So, we can only assume that the thermal comfort depends on factors such as air-temperature, humidity and air ventilation, all of these factors depending on the perception of each person. Therefore, to reach a thermal comfort in the building, it is necessary to have a balance of energy consumption for heating or cooling in correlation to the indoor temperature, humidity level and ventilation ratio. To have a meaningful estimation of the energy demand required by a passive house, we must first take into account the schedule of occupancy. Daily occupancy profile of the house was set in this analysis for two people. In this scenario, a thermal comfort is assumed when users were present in the house, and a reduced energy consumption for heating with 50% when the occupancy was zero. Simulation was performed for a period of one year using a time step of 1 h. The occupancy of the entire building is 1 for two people and 0.5 when there is only one person in the house. Between 9:00 AM and 5:00 PM, the house is not occupied, so that the energy consumed during this period of time is minimal (Figure 6). House heating starts in October and continues up to March (i.e. for 6 months). The energy demand for heating was estimated by taking into consideration the U-value and the envelope thickness. Additionally, Figure 7 presents the energy demand for energy consumption in correlation with the outside temperature and the solar radiation for the East Passive House. The total energy demand for heating in this simulation is 1978.62 kWh/year (Figure 7) for the entire building surface of 140 m2, which means an energy demand of 14.1 kWh/m2∙ year [28].
The energy demand is as low as 14.1 kWh/m2∙year due to the robust insulation of the house. In order to better understand the energy demands for such a house, Table 2 illustrates the energy demand for each area separately for the passive house simulated. The energy demand is in relation with the surface of the rooms, occupancy profile of the house with outside temperature and indoor temperature. The indoor temperature is taken between 20 °C and 26 °C. This passive house has high thermal inertia that preserves inside the house a temperature comfortable for occupants, with further reduces the energy for heating. A significant aspect in reducing energy consumption during winter is given by solar gains through the south facade of the house because of the large windows that allow solar radiation to enter the house. Figure 8 shows the heating power demand in relationship to the solar gain and the inside temperature for the living room during a day in January. The 3 rd day of January was random chosen for simulation purposes as a day of the winter season. Additionally, it can be seen from Figure 8 that the energy consumption for heating the living room increases slightly during the night, which is required to maintain a constant temperature of 20 °C in the room, but then, the energy consumption, drops to zero during the day from 13:00 to 18:00 PM. In the simulation, there are solar gains from 08:00 AM to 17:00 PM, which minimizes the energy demand for heating. During the night, the indoor temperature is constant and does not exceed 20 °C. During the day between 12:00 and 17:00 PM, the temperature increases to 22 °Cdue to the solar gains especially in the rooms with a south orientation such as bedroom, living and south bathroom.
In Figure 9, the results of the simulation of the indoor temperature on the 3rd of January are presented. During the night, the indoor temperature is constant and does not exceed 20 °C, but during the day, the temperature increases to 22 °C, especially in the rooms with a south orientation such as bedroom, living and south bathroom, because of the solar gains. The temperature in the other rooms remains constant during the day. 3. Actual data measurement results 3.1. Management data and interior comfort The building has a computerized system that uses the Smart Building Controller (SBC) software [28], which manage the building to ensure a pleasant environment for occupants with a minimal energy consumption. The SBC uses data from sensors placed in the rooms (see Figure 2 for sensor placements), to control all the devices installed in the building [28]. The sensors measure the following room parameters: the indoor temperature, CO2 concentration, humidity, luminosity [29]. Solar radiation and outside temperature are also measured with pyrometers and sensors placed on the roof. The occupants of the Passive House are PhD students who carry out activities related to their doctoral research from 9:00 AM to 18:00 PM. The measurements were taken four times per hour for 24 hours, following the schedule: 00:00; 00:10; 00:30; 00:40 every day. The monitoring of passive house started in 2013 [29]. The case study for these data analysis was performed only for the winter season (from October 2014 to March 2015, which represents 6 months). We were interested to understand how much energy is consumed by heating, ventilation, lighting and electrical appliances.
During daytime, the room temperature ranges between 20 °C and 23 °C, which represent a comfortable temperature for the occupants. Other important parameters that dictate the level of comfort for occupants is represented by CO2 concentration and humidity levels in the room, especially in office buildings or institutional buildings (i.e. schools and universities), where there are many people occupying a room at a given time. When the humidity is too low, people who live in the building may experience discomfort because of the dry air. Moreover, the humidity depends on the ventilation system that introduces fresh air in living spaces. Additionally, if fresh air is often circulated in the rooms, the humidity level increases. The Passivhaus Institut (PHI) specifies that when the fresh air is heated at a temperature of 20 °C, the humidity in the air decreases to 17.6% [30]. Figure 10 shows that the humidity measured in the house is within normal levels, having values between 17% and 27% at a temperature between 20 °C and 23 °C, which are typical values for winter period. The normal humidity level for a building varies between 30-70%, but differs from one building to another, depending on the type of building. Regarding the CO2 concentration in a given room, air quality inside the building depends on the rate of ventilation that introduces fresh air into the house. It is essential to monitor indoor air quality (IAQ) for health, comfort and productivity purposes. According to ASHRAE standard 62-2001, the ventilation rate depends on the floor area, which means that the air exchange per hour should be for residential buildings about 0.35 ACH but not less 15 cfm (cubic feet per minute) or about 7.5 L/s per person [31]. The admissible value of CO2 concentration in a habitable space should not exceed 800 ppm above outdoor air levels. For a house with sedentary occupancy, the CO2 concentration level may easily increase up to 1100 ppm. The CO2 concentration in buildings (such as schools, office buildings) is between 400 ppm and 1500 ppm, depending on the surface of the building [32]. In our case, we have measured in a typical day of winter a concentration of CO2 between 650 ppm and 667 ppm (Figure 10), which represents a normal value at a ventilation flow rate of 80 m3/h.
3.2. The energy consumption A detailed analysis of the energy consumed by the passive house was performed for the winter period which lasted for six months (i.e. from October to March). Table 3 shows that the heating system consumes most of the energy, followed by the electronics used in the living room, where the occupants spent most of the time. Another large portion of the energy consumed by the house is represented by the monitoring system that uses 558.35 kWh. The total energy consumption for heating in passive house was 1838.02 kWh/year; if this value is divided to the surface of the house, i.e. 140 m2, an energy consumption of about 13.12 kWh/m2∙year is obtained. October and November represent the lowest energy consumption for heating. The heating system was turned on during the last six days of October when the outside temperature dropped to 0 °C, thus maintaining an indoor temperature above 20 °C. To understand how much energy is consumed for heating to maintain a temperature that is comfortable, the results for two winter months in December and March are presented (Figure 11-12). December and January were the coldest months of the year, when the outside temperature dropped to -15 °C. For this reason, the energy consumption in December was as high as 425.12 kWh (3.03 kWh/m2) while the average inside temperature was kept at value of 20 °C as shown in Figure 11.
Figure 12 presents the energy consumption required for heating during March. The average indoor temperature was maintained at 23°C, although the outside average temperature fell to 0 °C in some days of March. From this analysis, it was observed that the energy consumption every day during the two months was between 10 kWh/day to 15 kWh/day. 3.3. Renewable electricity systems Due to the fact the energy consumption in buildings increased in the past years, there is a continuous pursuit for integrating photovoltaic panels on the facades and roofs of buildings. Electricity from photovoltaic panels is a clean energy, environmentally friendly and sustainable source [33]. For this reason, photovoltaic panels are ideal solutions for commercial building and residential houses. In this study, the passive house has, besides a heating system, a renewable energy source provided by photovoltaic panels installed on the roof of the house. These solar panels are made of polycrystalline Si having an output power of about 3 kW. The renewable system is connected to the local grid of University Politehnica of Bucharest and has the following specification presented in Table 4. PV modules are connected to an inverter that transforms the direct current (DC) to alternative current (AC), and a distribution board connected to the grid to export and import energy. An investigation of the PV system performance of energy delivered over one year was performed from September 15, 2014 to September 15, 2015 (Figure 13). The total energy supplied by the PV system over one year was 1556.5 kWh/year, and the rest of the required energy consumed being delivered by the grid. The maximum energy produced by the PV system was recorded in June, i.e. 229.4 kWh/month and the minimum energy delivered by PV was recorded in November, i.e. 19.50 kWh/month. The low electricity production recorded in November was due to the fact that November was the rainiest month of the year, and the intensity of solar radiation was very low. The daily average energy produced by PV in November was estimated to be about 0.92 kWh/day.
3.3.1 Economic investment calculation An economic investment for the PV system was performed with a simulation program named System Advisor Model (SAM). This software can be used to predict the energy production, but also may calculate the investment cost of a PV system connected to grid. SAM was developed by the National Renewable Energy Laboratory (NREL) for engineering and research. To perform this simulation, parameters such as PV system type, climate data and location must be run taking into account the price of energy delivered to the grid. In this simulation, the economic analysis of the cost of the investment was performed taking into account the following input data: i) the price of photovoltaic panels was 8831€, ii) the price for a single panel was 663€, iii) the cost of invertor was 1262€. The total investment cost was 12197€ (considering the price of photovoltaics panels, inverter and installation cost i.e. Figure 14). To find out the payback of the investment cost, the following economic parameters were considered: i) the sale price of the energy produced: 0.26 euro cents for 1 kWh, and ii) the state subsidy: 50% of the total investment. Figure 15 shows that, in the first year energy production (blue line), 50% of the total cost is recovered from the state. The return of investment turns positive starting with the 9th year of PV system operation. The investment is recovered from the surplus energy produced by the PV system, and the unused electricity is injected into the grid. The price of photovoltaic on the economic market varies from one day to another. Therefore, the investment may turn positive much faster when the PV system cost
is reduced by more than 50%. For this PV system, the total electricity production was 2307.1 kWh during one year (Figure 16). In the winter months, the electricity provided by the PV system is half compared to the summer months, due to the fact that the solar radiation is diffused in winter and weather conditions are bad.
The electricity production of the PV system is the highest from April to August as shown by both measured and simulation data. In addition, the actual data measured for energy production was 1556.5 kWh/year during one year, compared to the energy production of 2307.1 kWh obtain by simulation. This difference can be explained by the fact that the PV system is assumed in simulation to operate in ideal conditions.
4. Discussion The purpose of this study was to analyze the energy consumption and production of a passive house in Romania by comparing the actual performance with simulation data for similar conditions. Simulation of the energy consumptions for a real house is very important to understand the actual energy consumption and generation, and where are the largest differences. Based on the occupancy schedule, the simulated demand of energy for heating was 14.1 kWh/m2∙year, while the actual energy consumption was 13.12 kWh/m2∙year. The energy demand for space heating is low in winter due to the solar gains promoted by both south orientation of the house and large windows. Simulation results showed that the temperature increased by two degrees in the rooms with south orientation such as living room, office, south bedroom and south bathroom. Beside energy performance, other parameters such as indoor temperature, CO2 and humidity levels are critically important for a Passive House analysis. The actual measurements of humidity and CO2 concentration showed that their values are within the normal range for the Passive House. In addition, the indoor temperature during the day was comfortably kept between 20 °C and 22 °C during the winter season. The electricity generated from PV system during one year was 1556.5 kWh/ year, the rest of the necessary energy for consumption being supplied by the grid. The economics of PV system integration were analyzed by calculating the return of investment. Because the initial investment cost is high at the actual PV system prices, the return of investment turns positive only after 9 years. After the investment is recovered, the PV system becomes profitable. This study shows how a Passive House’s energy performance responds to new concepts such as those introduced in this study: heating or cooling system depending on the season, monitoring policy implemented in the energy management of the house and the use of renewable electricity sources. Besides this, a critical role is played by the reduction of the energy consumption of a house. This study shows that it is possible to have a pleasant thermal comfort maintained in the house at low energy consumption when customized isolation for a given location is used. This case study represents a practical model for the new houses that will be built in Romania. 5. Conclusions This paper presents a study of an efficient energy building, built in Romanian climat condition, according with the passive house standard. The building combines efficient
HVAC systems and integretes renewable energy system to generate electricity. We studied the evolution of the building and recorded the energy consumption during 6 months. The results show that the building has a low energy consumption mainly due to the SBC policy of the building. This study brings essential information that can be used in the future for all the buildings that will be built in Romania, because most of the buildings are residential and represent 80%of the buildings, with a large energy consumption for heating (i.e. 56% of the total energy consomption). Additionally, the law imposed by Eurpean Comision concerning that all the buildings should be nearly zero energy building (nZEB) by the year 2018, Romania is required to focus on the reduction of energy consumtion and emissions of greenhouse. In the future, this passive house can be a plus energy building, if doubls the number of photovoltaic panels installed or may be just a zero energy building. This pasive house represents a model of energy efficient building, sustainable and ecological, and represents a solution for the future residential houses. Acknowledgment The work has been funded by the Sectorial Operational Programmer Human Resources Development 2007-2013 of the Ministry of European Funds through the Financial Agreement POSDRU/159/1.5/S/132395. This passive house was built during a research project developed through a partnership between the University POLITEHNICA of Bucharest (UPB), Technical University of Civil Engineering Bucharest (UTCB), University of Architecture and Urbanism “ION MINCU” (UAIM), Institute for Studies and Power Engineering (ISPE), Academy of Romanian Scientists (AOSR), Electro-Technical Research Institute (ICPE) and a private company (AGECOM). Reference [1] Directive 2009/28/EC of the European Parliament and of the Council, Official Journal of the European Union (2009) http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0028.
[2] Badescu V, Simulation analysis for the active solar heating system of a passive house, Journal of Applied Thermal Engineering 25 (2005) 2754-63. [3] A. Buonomano, F.Calise, G. Ferruzzi, A. Palombo, Dynamic energy performance analysis: Case study for energy efficiency retrofits of hospital buildings, Journal of Energy 78 (2014) 555-72. [4] L. Wang, J. Gwilliam, P. Jones, Case study of zero energy house design in UK, Journal of Energy and Buildings 41 (2009) 1215–22. [5] Directive 2009/29/EC of the European Parliament and of the Council, Official Journal of the European Union (2009) http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32009L0029.
[6] Jurgen Schniedersa, Andreas Hermelink. CEPHEUS results: measurements and occupants’ satisfaction provide evidence for Passive Houses being an option for sustainable building. Energy Policy. 34 (2006) 151-71. [7] V. Badescu , M. D. Staicovici, Renewable energy for passive house heating. Model of the active solar heating system, Journal of Energy and Buildings 38 (2006) 129–41. [8] IEEA, The passivhauss standard in european warm climates, EC funded project: Marketable Passive Homes for Winter and Summer Comfort (2007)
http://www.eerg.it/passiveon.org/CD/1.%20Technical%20Guidelines/Part%203/Part%203.pdf. [9] Wolfgang Feist, Certification criteria for residential Passive House buildings, Passive House Institute (2013) http://www.passiv.de/downloads/03_certification_criteria_residential_en.pdf. [10] G.E. Vlad, C. Ionescu, H. Necula, Simulation and Energy Efficiency Evaluation of a Low-Energy Building. Journal of Sustainable Energy III (June 2012). [11] J. Schnieders W. Feist, L. Rongen, Passive Houses for different climate zones, Journal of Energy and Buildings 105 (15 October 2015) 71–87. [12] W. Feist, J. Schnieders, V. Dorer, A. Haas, Re-inventing air heating: Convenient and comfortable within the frame of the Passive House concept, Journal of Energy and Buildings 37 (2005) 1186-203. [13] H.M. Taleb, Using passive cooling strategies to improve thermal performance and reduce energy consumption of residential buildings in U.A.E. buildings, Journal of Frontiers of Architectural Resarch 3 (2014) 154-65. [14] Building Research Establishment Environmental Assessment Method - BREEAM http://wwwbreeamcom.
[15] Ledership in Energy and Environmental Design - LEED http://wwwusgbcorg/leed.
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http://passivehousecom/02_informations/01_whatisapassivehouse/01_whatisapassivehousehtm.
[17] M.L. Persson, A. Roos, M. Wall, Influence of window size on the energy balance of low energy houses, Journal of Energy and Buildings 38 (2006) 181–8. [18] A. Audenaert, S.H. De Cleyn, B. Vankerckhove, Economic analysis of passive houses and low-energy houses compared with standard houses, Journal of Energy Policy 36 (2008) 47-55. [19] L. Georges, C.Massart, G.Van Moeseke , A.De Herde, Environmental and economic performance of heating systems for energy-efficent dwellings: Case of passive and lowenergy, Journal of Energy Policy 40 (2012) 452–64. [20] D. Dan, C. Tanasa, V. Stoian, S. Brata, D. Stoian, T. Nagy Gyorgy, S.C. Florut. Passive house design - An efficient solution for residential buildings in Romania. Energy for Sustainable Development 32 (2016) 99-109. [21] Ioana Udrea, Cristian Croitoru, Ilinca Nastase, Ruxandra Crutescu, Viorel Badescu. Thermal comfort in a Romanian Passive House. Preliminary results. Energy Procedia 85 (2016) 575-583. [22] Viorel Badescu, Nadine Laaser, Ruxandra Crutescu. Warm season cooling requirements for passive buildings in Southeastern Europe (Romania). Energy 35 (2010) 3284-3300. [23] G.E. Vlad, C. Ionescu, H. Necula, A. Badea , Simulation of an air heating/cooling system that uses the ground thermal potential and heat recovery, U.P.B. Sci. Bull. 75 (2013). [24] A. Badea T.Baracu, C. Dinca, D. Tutica, A life-cycle cost analysis of the passive house “POLITEHNICA” from Bucharest, Journal of Energy and Buildings 80 (2014) 542-55. [25] Energy U.S. Department of Energy, EnergyPlus Energy Simulation Software (2015). http://apps1eereenergygov/buildings/energyplus/?utm_source=EnergyPlus&utm_medium=redirect &utm_campaign=EnergyPlus%2Bredirect%2B1.
[26] Meteonorm Software, offers you simple access to accurate data for any place on Earth: Irradiation, temperature and more weather parameters are available (2015) http://meteonorm.com.
[27] ASHRAE Standard 55-2004, Thermal Environmental Conditions for Human Occupancy (2004) http://wwwalmasesepahancom/fh/download/ASHRAE_Thermal_Comfort_Standardpdf. 2004.
[28] V. Tanasiev, H.Necula, S. Costinas, G. Sava, A. Badea, Achieving energy savings and thermal comfort through intermittent heating in very low energy buildings, International Conference on Environment and Electrical Engineering (2015) 2183 - 8. [29] M.B. Carutasiu, V.Tanasiev, C. Ionescu, A. Danu, H. Necula, A. Badea, Reducing energy consumption in low energy buildings through implementation of a policy system used in automated heating systems, Journal of Energy and Buildings 94 (2015) 227-39. [30] Passiv House Institute, Ventilation and Humidity - Their conection explained (2007) http://www.passivhaustagung.de/Passive_House_E/ventilation_and_humidity.htm.
[31] ASHRAE Standard 62-2001, Ventilation for Acceptable Indoor Air Quality (2001). [32] Ashrae handbook committeeFundamentals (2001) http://systemssolution.net/cadtechno/0%20SAMPLE/SPECs%20&%20DETAILS/BOOKS%20MECHANI CAL/HVAC/ASHRAE%20HVAC%202001%20Fundamentals%20Handbook.pdf.
[33] M.I. Mihai, V.Tanasiev, A. Badea and R. Vidu. The influence of climatic factors on the performance of photovoltaic panels. ARA Proceedings. 39 (2015) 70. http://dx.doi.org/10.14510/39ARA2015.3915
Figure 1. The Passive house from UPB campus, simulated in EnergyPlus.
Figure 2. Building plan: ground floor (a) and second floor (b). Sensor placement and distribution are also shown in blue in the floor plans
Figure 3. Building systems of the East Passive House UPB, Ro [24]. 1) Solar collector; 2) cold water pipe; 3) hot water tank; 4) domestic hot water outlet, 5) electric resistance heat; 6) MVHR; 7) EAHX by-pass; 8) condensate drain well, 9) EAHX, 10) electric radiant panel.
Figure 4. Monthly solar radiation distribution for Bucharest, Romania.
Figure 5. Daily temperature Bucharest, Romania.
distribution
Figure 6. Hourly occupancy profiles of the passive house.
Figure 7. Energy demand simulated for heating according to outside temperature and solar radiation.
for
Figure 8. The simulated energy consumption for the living room on the 3 rd January.
Temperature [°C]
22.5 22
South bedroom Living room
21.5 21 20.5
20 1
3
5
7
9
11 13 15 Time (hours)
17
19
21
23
Figure 9. Building simulated indoor temperature for each room on the 3rd of January (Note: the temperature for the following rooms was 20 oC: North bedroom, north bathroom, north deposit, technic room, and vestibule.
Figure 10. The CO2 concentration and humidity, during the 2nd of January, 2015.
Figure 11. Energy consumption for heating in December of 2014.
Figure 12. Energy consumption for heating in March of 2015.
Figure 13. The energy production 2014-2015.
Figure 14. Investment cost of the PV system. 20,000 15,000
EURO (€)
10,000 5,000 0 -5,000 Cumulative payback - expenses excluded (€)
-10,000
Investment recovery (€)
-15,000 -20,000 1
3
5
7
9
11
13
15
PERIOD (YEARS)
Figure 15. Payback time of the investment cost
17
19
21
23
25
Figure 16. The energy production of PV system in the simulation
Tabel 1. The U-values and thickness of each construction elements. Component buildings
of
Exterior Wall
Roof
Ground floor
Party wall Neighbor
Windows Door
to
Elements construction
of
Thickness [mm]
Interior plaster 22 Cellular concrete Ytong 250 Mineral wool 300 U-value 0.122 [W/(m2∙K)] Plaster 22 Reinforced concrete 130 Mineral wool 400 U-value 0.107 [W/(m2∙K)] Parquet 22 OSB board 8 Lightly reinforced 50 EPS high density 150 Reinforced concrete 120 XPS polystyrene 180 Lightly reinforced 50 U-value 0.114 [W/(m2∙K)] Plaster 22 Solid brick 250 Plaster 22 U-value 1.594 [W/(m2∙K)] Component G-value [W/m2∙K] Low-E Saint Gobain Glass 0.5 REHAU frame REHAU door -
U-value λ [W/(m∙K)] 0.800 0.270 0.040 0.800 1.740 0.040 0,200 0.130 1.100 0.040 1.740 0.040 1.100 0.8 0.8 0.8 U-value [W/(m∙K)] 0.6 0.78 0.8
Tabel 2. Energy demand for East Passive House estimated using the same procedure as detailed previously [28]. Zone area
Area [m2]
Living room Technical room Hall North bathroom Deposit North bedroom Office South bedroom South bathroom Total [m2] Total [kWh/m2∙year]
70.4 5.16 16.2 6.75 4.39 12.6 12.43 17.64 8.64 140 14.1
Windows surface [m2] 15.27 0 0 1.01 1.01 1.64 2.34 4.38 1.01
Energy demand for heating [kWh/year] 1103.17 52.17 90.26 67.26 102.33 203.77 121.67 156.99 62.97
Tabel 3. Energy consumption (kWh) measured in the building during 6 months, (2014 - 2015, represents the winter period) Period
Electronic devices [kWh]
Lights
Appliances for kitchen [kWh]
Electrical resistance [kWh]
Ventilation
October
24.00
5.23
18.70
50.65
6.53
91.82
November
356.23
7.83
14.98
197.65
48.51
93.62
December
242.08
12.64
49.62
425.12
79.15
99.21
January
375.23
4.95
30.51
445.96
45.20
92.61
February
609.06
0
56.31
258.74
0
85.10
March
48.18
0
141
459.90
68.31
95.99
Months total consumption
1654.78
30.65
311.12
1838.02
247.7
558.35
(Months)
[kWh]
[kWh]
Monitoring system [kWh]
Tabel 4. The PV parameters specification and inverter: Parameters (photovoltaics)
Value
Parameters (Inverter)
Value
Rated power
230.7 W/PV
Nominal power
3.0 kW
Area
~ 22 m2
Operating voltage
120-580 V
Short circuit current
8.24 A
Number
1
Open circuit voltage
36.7 V
Frequency
50/60 Hz
Modules
13 PV
-
-
Total rated power
3 kW
-
-