First steps towards low energy buildings: how far are Chilean dwellings from nearly zero-energy performances?

Available online at www.sciencedirect.com

ScienceDirect

Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Available Energy Procedia 00 (2017) 000–000

ScienceDirect ScienceDirect

www.elsevier.com/locate/procedia

Energy Procedia Procedia 00 132(2017) (2017)000–000 81–86 Energy www.elsevier.com/locate/procedia

11th Nordic Symposium on Building Physics, NSB2017, 11-14 June 2017, Trondheim, Norway

First steps towards low energy buildings: how far are Chilean The 15th International Symposium on District Heating and Cooling dwellings from nearly zero-energy performances? Assessing the feasibility ofa*,using heata demand-outdoor Daniela Besser Frank the U. Vogdt temperature function for a long-term district heat demand forecast Technische Universität Berlin, Gustav-Meyer-Allee 25, 13355 Berlin, Germany aa

I. Andrića,b,c*, A. Pinaa, P. Ferrãoa, J. Fournierb., B. Lacarrièrec, O. Le Correc a

IN+ Center for Innovation, Technology and Policy Research - Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon, Portugal b Veolia Recherche & Innovation, 291 Avenue Dreyfous Daniel, 78520 Limay, France c Département Systèmes Énergétiques et Environnement - IMT Atlantique, 4 rue Alfred Kastler, 44300 Nantes, France

Abstract

In Chile, the nearly zero-energy goal for new dwellings is scheduled by 2035. Recently, a draft regulation was published, highly tightening the energy-environmental requirements within the building regulations. This study uses dynamic thermal simulations to evaluate the energy performance of new Chilean dwellings and the impact these new Abstract requirements would produce along the country’s climatic differences. In addition, strategies addressing the remaining causes of energy loss are proposed, in an attempt to approach Chilean dwellings to nearly zero-energy performances.

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the © 2017 The Authors. Published by Elsevier Ltd. ©greenhouse 2017 The Authors. Published Ltd. gas emissions frombytheElsevier building sector. These systems require high investments which are returned through the heat Peer-review under responsibility of organizing committee of Symposium on Physics. Peer-review of the theconditions organizingand committee of the the 11th 11th Nordic Nordic Symposium on Building Building sales. Due under to theresponsibility changed climate building renovation policies, heat demand in thePhysics. future could decrease, prolonging the investment return period. Keywords: housing energy performance; thermal comfort; building regulations; low energy buildings The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district 1. Introduction renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. Chile is ashowed developing country that aims to reach development withinof the decades, whichfor is some a process that The results that when only weather change is considered, the margin errornext could be acceptable applications requires energy. Nevertheless, the 20% Chilean energy matrix relaysconsidered). on importedHowever, energy sources, highly exposing (the error in annual demand was~70% lowerofthan for all weather scenarios after introducing renovation the countrythe to error the international price fluctuation. The sector accounts for ~26% of the consumed scenarios, value increasedenergy up to 59.5% (depending on the building weather and renovation scenarios combination considered). energy, where housing represents ~78% on [1].average Therefore, efficiency an important role intothethe The value of slope coefficient increased withinenergy the range of 3.8%has upstarted to 8% playing per decade, that corresponds decrease in theagenda, number with of heating hours of 22-139h during the heating (depending the combination of weather and government’s several goals addressing energy use in season buildings. Amongonthem, that all new buildings renovation considered). the other function intercept increased for 7.8-12.7% per decade on the would meet scenarios the energy efficiency On standards of hand, the OECD (Organisation for Economic Co-operation and(depending Development) scenarios). The values could[2]. be used modify thethe function parameters the scenarios and bycoupled 2050, and by 2035 in the casesuggested of dwellings Beingtothe aim of European OECD for members to buildconsidered, only nearly improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and *Cooling. Corresponding author. Tel.: +49-0157-3190-8484. E-mail address: [email protected]

Keywords: Heat demand; Forecast; Climate change 1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the organizing committee of the 11th Nordic Symposium on Building Physics.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.

1876-6102 © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the organizing committee of the 11th Nordic Symposium on Building Physics 10.1016/j.egypro.2017.09.642

Daniela Besser et al. / Energy Procedia 132 (2017) 81–86 Author name / Energy Procedia 00 (2017) 000–000

82 2

zero-energy buildings from 2021 onwards, the goal is ambitious and challenging, and it would require to highly tighten the current building standards and that the market would evolve accordingly. The current Chilean Thermal Regulation (TR) limits the thermal transmittance of roofs since the year 2000, plus walls and suspended floors, together with windows proportion according to glazing type since 2007. The requirements are distinguished according to the heating need of each location, i.e. heating degree-days, dividing the country in seven ‘thermal zones’. Based on a study undertaken by CDT [3], the enactment of the TR made possible to reduce in more than half the average heating energy a dwelling would demand for providing thermal comfort, as shown in Figure 1a. These performances, however, are still far from highly efficient, low energy buildings, as demonstrated by several studies [4,5]. Consequently, the 3rd Stage of the TR, on trial basis since 2012, qualifies the energy performance of dwellings from A (most efficient) to G (less efficient), and rates with the letter ‘E’ those dwellings whose thermal envelopes strictly comply with the current TR limiting values. The dwelling’s energy rating is calculated based on the percentage of energy savings the dwelling achieves when compared with its ‘E’ performance (i.e. reference building), as shown in Figure 1b.

KWh/m2 year

300

reference building

200

zone 1-2

100

zone 3-4-5

0

268

159

111

111

before TR

1st stage TR

2nd stage TR

3rd stage TR

(before 2000)

(2000)

(2007)

(2012)

zone 6-7

reference energy demand A

B A

C B

A

D C B

E D C

E D

E

F

G

F

G

F

G

100 90 80 70 60 50 40 30 20 10 0 -10 -20 -30 -40 -50 % percentage of energy savings

Fig. 1. (a) Average heating energy demand of Chilean dwellings before and after the TR; (b) percentage of energy savings used in the Chilean energy qualification of dwellings system when comparing the energy demand between the assessed and the reference building.

Aware of the still existing big scope for improvement, the Chilean Ministry of Housing and Urban Planning (MINVU) commanded an update proposal for the TR, which is currently under public consultation. The draft, called ‘Technical Norm MINVU 11’ (NTM-11) [6], highly tightens the TR limiting values, together with addressing determining factors when aiming for energy efficiency and environmental comfort, not previously regulated: thermal transmittance of the whole building envelope, airtightness, ventilation for air quality, condensation and mould growth risk, thermal bridges and solar protection. This study aims not only to assess the effect of these new requirements in the energy performance of typical dwellings along the country, but also, to explore the next steps that should need to be taken in order to further reduce the dwellings energy demand and approach it to the nearly zero-energy goal. 2. Methodology The study uses dynamic thermal simulations with ‘Design Builder’ software to predict the variation on the annual energy demand for space conditioning that would arise from the implementation of the NTM-11 standard in three case studies in four different Chilean locations. A parametrical approach was utilized to separately understand the effect the new requirements would produce. The assessed parameters were: thermal transmittance of the building envelope, solar control, envelope airtightness, and ventilation for air quality. Complementarily, the influence of thermal mass and orientation were evaluated. In parallel, the energy balance of the case studies was analyzed, to identify the main causes of energy loss and search for scope for improvements. Based on data gathered from the National Statistics Institute of Chile (www.ine.cl), three case studies were chosen to represent typical configurations found in the recently built Chilean housing stock: two detached, single-family homes, of one and two-storeys and 50 and 106m2 respectively, and a 1614m2, five-storey multi-family building with apartments ranging from 34 to 58m2. For the walls, the most frequently used materials were assessed, hence simulating the single family houses both in lightweight and heavyweight construction systems, whereas the multi-family building was only simulated in concrete. In this last case, the effect of orientation was complementary assessed.



Daniela Besser et al. / Energy Procedia 132 (2017) 81–86 Author name / Energy Procedia 00 (2017) 000–000

83 3

Table 1. Simulation code and complementary information about building materials, locations and simulation sets. 1

Case study number

A

Building materials

- ZA -

Location (NTM-11 thermal zone)

-0-

Simulation set A

A

Brickwork walls and partitions, concrete slab-on-ground, timber-frame roof

B

Timber-frame walls and partitions, concrete slab-on-ground, timber-frame roof

C

Concrete walls and aerated concrete partitions, concrete slab-on-ground, timber-frame roof

A

Antofagasta (23°27’ S, 70°26’ W), desert with abundant cloud cover climate

D

Santiago (33°26’ S, 70°41’ W), warm temperate continental climate

E

Concepción (36°47’ S, 73°70’ W), warm temperate maritime climate

I

Punta Arenas (58°80’ S, 70°53’W), cold steppe climate

1

Building complying with the limiting U-values of the TR

2

Building complying with the limiting U-values and modified solar factors of the NTM-11

3

As set 2, plus reduction on air infiltration rates

4

As set 3, plus mechanical ventilation for air quality

0

As set 1, but considering ventilation for air quality as in set 4. Since ventilation normally increases the energy demand, this sets aims a fairer comparison of a building when complying with the current TR and the proposed NTM-11 limiting values, but considering the same air quality.

0°

Orientation (plan rotation regarding indicated north)

Locations

D

Case study 1

Case study 2

Case study 3

E

NTM 11 ZONES

A

A B C D E F G H I

D

z1 z1

E

GF

0 1 2

NTM 11 ZONES A B C D E F G H I

z1

z1

I

GF

4m 0 1 2

0 1 2 4m

GF

z1 z2

z1 GF

GF

4m

z2 GF 0 1 2

z1

z2

z2

FF FF FF 0 1 2 4m 4m0 1 2 4m

z6 NORTH z6z1 z6 z3 z3 z3 z7 z7 z7 z4 z2 z2 z5 z5 z4 z5 z4 z1

NORTH NORTH

Floor 1-4 Floor 1-4 Floor 1-4 0 1 2 4m 0 1 2 4m 0 1 2 4m

Fig. 2. Selected locations, case studies and zones (z) considered for the thermal simulations

Façade / zone (z)

NTM 11 1

2 S

3-90° N

S

1

2

3

E-W

Roof

N

S

E-W

E-W

All

z1

z6

z7

A (1)

4.0

0.84 3.35 5.8 5.8 5.8

5.8

5.8

5.8

5.8

5.8

5.8 5.8

5.8

1.00

-

-

-

-

-

D (3)

1.9

0.47 3.35 5.8 5.8 5.8

5.8

2.8

2.8

2.8

2.8

2.8 2.8

2.8

1.00

-

-

-

-

-

E (4)

1.7

0.38 3.35 5.8 5.8 5.8

5.8

2.8

2.8

2.8

2.8

2.8 2.8

2.8

1.00

-

-

-

-

-

I (7)

0.6

0.25 3.35 5.8 2.8 2.8

2.8

2.8

1.8

1.8

1.8

1.8 1.8

1.8

1.00

-

-

-

-

-

A

2.1

0.84 3.35 5.8 5.8 5.8

5.8

5.8-0.36

5.8-0.75

2.8

5.8

5.8 5.8

5.8-0.58

0.70 0.56 0.43 0.70 0.73 0.46

D

0.6

0.38 1.20 5.8 2.8 2.8

5.8

2.8-0.36

2.8-0.67

1.3

5.8

5.8 5.8

2.8-0.50

0.56 0.56 0.43 0.70 0.73 0.46

E

0.5

0.33 1.00 2.8 2.8 2.8

2.8

2.8-0.36

2.8

1.3

2.8

2.8 1.8

1.8

0.56 0.56 0.43 0.70 0.73 0.46

I

0.35 0.25 0.80 2.8 2.8 1.8

2.8

2.8

1.8

1.3

2.8

2.8 2.8

1.3

0.28 0.56 0.43 0.70 0.73 0.46

All

N

3-0°

Ventilation6

Infiltration5

U and g Glazing3,4

U door 1

Case study

TR

U roof

U wall1

I

Location1

Table 2. U-values [W/m2K], g-values [-], and infiltration and ventilation rates [h-1] used for the simulations

z1-2 z1-5

The given letters correspond to the NTM-11 thermal zone where the cities are located, whereas the numbers in brackets convey the corresponding TR thermal zone. 2 In zone A (1), better U-values than the limiting ones, of 2.1 W/m2K and 1.7 W/m2K, were used for the timber-frame walls when TR and NTM-11 respectively, since worse U-values are practically impossible to obtain using this construction system, even when uninsulated. 3 The modified solar factor requirements were achieved by reducing the glazing g-values, which are only provided when different from default. Default g-values utilized: single glass U 5.8 = 0.86; double glass U 2.8 = 0.76; double glass, low emissivity U 1.3 = 0.72; double glass, low emissivity, argon filled U 1.3 = 0.64. 4 The limiting n50 values were multiplied by 0.07 to obtain the nominal infiltration rates [7]. In location A, with no requirements, an n50 value of 10h-1 was tested. 5 The ventilation rates (Qv), in L/s, were calculated as proposed by the NTM-11 using Qv = 0.15 (floor area) + 3.5 (amount of bedrooms + 1) [8].

Daniela Besser et al. / Energy Procedia 132 (2017) 81–86 Author name / Energy Procedia 00 (2017) 000–000

84 4

The case studies were simulated in four of the nine thermal zones the NTM-11 proposes, and simulations were divided into five sets according to the parameters to be explored. The case studies, building materials, locations and simulation sets are briefly explained in Table 1 and Figure 2. The former also provides an explanation of the simulation code used to identify every simulation. Complementarily, Table 2 summarizes the parameters to vary according to thermal standard and location. For the energy demand prediction, heating and cooling were simulated considering ideal loads, at 20°C and 26°C air temperature respectively, whenever when demand. Internal gains were considered a constant value of 3.8W/m2. For the floors, the monthly temperatures under the slab were obtained using the slab preprocessor tool of Energy Plus, allowing to account for the effect of the vertical perimeter insulation the NTM-11 proposes. 3. Results and discussion

Case study 1

Figure 3 charts the simulated annual energy demand for heating and cooling of the three case studies, considering two construction systems for the single-family houses and two orientations for the multi-family building, in the four selected locations. From the results it becomes clear that heating is the main concern along the country, whereas cooling loads are very reduced or even inexistent, but more frequent in lightweight constructions and highly glazed east-west façades. When comparing the energy performance of the case studies complying with the limiting values of the TR and NTM-11 thermal standards using equivalent ventilation rates (sets 0 and 4), the achieved energy savings were 18 to 58% in Antofagasta, 35 to 51% in Santiago, 46 to 56% in Concepción and 42 to 49% in Punta Arenas. ZA - Antofagasta

400 350

39%

300

ZD - Santiago

18%

45%

ZE - Concepción

47%

48%

ZI - Punta Arenas

48%

42%

42%

250 200 150 100

Case study 2

1B-ZI-4

1B-ZI-3

1B-ZI-2

1B-ZI-1

1B-ZI-0

1A-ZI-4

1A-ZI-3

1A-ZI-2

1A-ZI-1

1A-ZI-0

1B-ZE-4

1B-ZE-3

1B-ZE-2

1B-ZE-1

1B-ZE-0

1A-ZE-4

1A-ZE-3

1A-ZE-2

1A-ZE-1

1A-ZE-0

1B-ZD-4

1B-ZD-3

1B-ZD-2

1B-ZD-1

1B-ZD-0

1A-ZD-4

1A-ZD-3

1A-ZD-2

1A-ZD-1

1A-ZD-0

1B-ZA-4

1B-ZA-3

1B-ZA-2

1B-ZA-1

1B-ZA-0

1C-ZA-4

1C-ZA-3

1C-ZA-2

1C-ZA-1

0

1C-ZA-0

50

300 250

47%

200

21%

51%

50%

56%

54%

47%

45%

150 100

2B-ZI-4

2B-ZI-3

2B-ZI-2

2B-ZI-1

2B-ZI-0

2A-ZI-4

2A-ZI-3

2A-ZI-2

2A-ZI-1

2A-ZI-0

2B-ZE-4

2B-ZE-3

2B-ZE-2

2B-ZE-1

2B-ZE-0

2A-ZE-4

2A-ZE-3

2A-ZE-2

2A-ZE-1

2A-ZE-0

2B-ZD-4

2B-ZD-3

2B-ZD-2

2B-ZD-1

2B-ZD-0

2A-ZD-4

2A-ZD-3

2A-ZD-2

2A-ZD-1

2A-ZD-0

2B-ZA-4

2B-ZA-3

2B-ZA-2

2B-ZA-1

2B-ZA-0

2C-ZA-4

2C-ZA-3

2C-ZA-2

2C-ZA-1

200 150

58%

100

33%

44%

35%

56%

46%

49%

49%

heating demand (kWh/m² a)

3-ZI-4-90°

3-ZI-3-90°

3-ZI-2-90°

3-ZI-1-90°

3-ZI-0-90°

3-ZI-4-0°

3-ZI-3-0°

3-ZI-2-0°

3-ZI-1-0°

3-ZI-0-0°

3-ZE-4-90°

3-ZE-3-90°

3-ZE-2-90°

3-ZE-1-90°

3-ZE-0-90°

3-ZE-4-0°

3-ZE-3-0°

3-ZE-2-0°

3-ZE-1-0°

3-ZE-0-0°

3-ZD-4-90°

3-ZD-3-90°

3-ZD-2-90°

3-ZD-1-90°

3-ZD-0-90°

3-ZD-4-0°

3-ZD-3-0°

3-ZD-2-0°

3-ZD-1-0°

3-ZD-0-0°

3-ZA-4-90°

3-ZA-3-90°

3-ZA-2-90°

3-ZA-1-90°

3-ZA-0-90°

3-ZA-4-0°

3-ZA-3-0°

3-ZA-2-0°

0

3-ZA-1-0°

50 3-ZA-0-0°

Case study 3

0

2C-ZA-0

50

cooling demand (kWh/m² a)

Fig. 3. Simulated annual energy demand for space conditioning of the case studies in the selected locations and percentage of energy savings when comparing set 0 and set 4



Daniela Besser et al. / Energy Procedia 132 (2017) 81–86 Author name / Energy Procedia 00 (2017) 000–000

Case study 1 1B-ZD-0 1A-ZD-3

1A-ZD-1 1B-ZD-3

Case study 2 1B-ZD-1 1A-ZD-4

1A-ZD-2 1B-ZD-4

150

100

100

50

50

0

0

-50

-50

-100

-100

2A-ZD-0 2B-ZD-2

2B-ZD-0 2A-ZD-3

2A-ZD-1 2B-ZD-3

Case study 3 2B-ZD-1 2A-ZD-4

2A-ZD-2 2B-ZD-4

150

3-ZD-0_0° 3-ZD-2_0°

3-ZD-0_90° 3-ZD-2_90°

3-ZD-1_0° 3-ZD-3_0°

3-ZD-1_90° 3-ZD-3_90°

100 50

-50 -100

ventilation

infiltration

roof

floor

walls

glazing

internal gains solar gains

ventilation

infiltration

roof

floor

walls

glazing

solar gains

-150

internal gains

ventilation

infiltration

roof

floor

walls

glazing

0

internal gains solar gains

ZD - Santiago

150

1A-ZD-0 1B-ZD-2

85 5

Fig. 4. Main causes of heat gains and losses [kWh/m2 a] of case studies 1, 2 and 3 in Santiago.

Antofagasta represents the thermal zone with the lowest energy needs in the country, as confirmed by the results. Even when the strengthening of the requirements mainly concerns to walls, the new limiting values produced a considerable impact on the energy demand of the case studies, reducing it by ~40% in the heavyweight cases. This effect could not be completely appreciated in the lightweight constructions, since uninsulated timber-frame walls already provide better U-values than the limiting ones in both standards. The high influence of thermal mass, however, can be observed in both the heating and cooling energy demand, achieving heavyweight constructions considerably better performances than lightweight ones. The reduction on the g-values of the highly glazed façades was found positive in the reduction of cooling loads, but orientation was found to be more influential. With regards to air infiltrations, even when no requirements are settled by the NTM-11, a slight reduction from 1.0h-1 to 0.7h-1 was assessed, which further reduces the total energy demand by ~8%, in spite of increasing the cooling loads. In Santiago and Concepción the obtained values for energy demand and savings were of similar magnitudes. In these locations, reducing the U-values of the building envelope and limiting solar access lessened by 27 to 48% the energy demand of the case studies and had a higher impact than reducing the air infiltrations in all cases. The combination of both strategies, however, managed to reduce in more than half the energy demand in most of them. With regards to windows, case 3 surpasses the NTM-11 allowed proportions on its north-south orientation (0°) but it complies with them when east-west oriented (90°). The case 3-0° was therefore simulated using a higher performance window with a glazing U-value of 1.3 W/m2K in the façades that exceeded the allowed proportion, obtaining better results than in the case 3-90°. In the last one, not only heating but also cooling loads were higher, despite the reductions on the glazing g-value, supporting the idea that orientation is determining with this regard. Similarly as in Antofagasta, thermal mass influenced the heating and cooling needs in both locations, but at a lower degree in Concepción. Punta Arenas represents the thermal zone with the highest heating needs, as can be seen in the results. Here, every one of the assessed set of parameters produced a considerable impact in the results, but neither thermal mass nor orientation were shown to be significant on them. The tightening of the envelope U-values reduced the heating demand by ~22% in the single-family houses and by ~15% in the multi-family home. Similarly as in Santiago and Concepción, the multi-family home exceeded the allowed windows proportion, yet in both assessed orientations. Thus, the same described procedure was used for the simulations, obtaining similar results and savings in both orientations. The influence of limiting the air infiltrations was found to be the most influential parameter, especially in the multi-family building, further reducing its heating demand by ~50%, and by ~30% in the single-family cases. With regards to ventilation, the provision of a constant air flow for air quality at ambient temperature considerable rose the energy demand in all cases and locations. The NTM-11 requires all dwellings to be equipped with mechanical ventilation, but the methodology for calculating the ventilation rates do not provide a method to account for the influence of air infiltrations. Therefore, spaces might be over-ventilated, unnecessarily increasing energy losses. Indeed, when analyzing the energy balance of the case studies in Santiago, presented in Figure 4, both ventilation and air infiltrations are shown to be major causes of heat loss, despite the considerable reductions of the latter due to the NTM-11 new airtightness requirements. The charts also convey the benefits of tightening the U-value of walls,

86 6

Daniela Besser et al. / Energy Procedia 132 (2017) 81–86 Author name / Energy Procedia 00 (2017) 000–000

but they still remain as an important cause of heat loss, especially in single-family houses. In these typologies, floors on-ground are also a major cause of heat loss, where no noticeable improvements due to the perimeter vertical insulation were observed. On the contrary, the heat losses through the roof are the less significant ones in all cases. The strengthening of the windows requirements can only be noticed in case 2, still allowing scope for improvement in all cases. Complementarily, the influence of the reductions of the glazing g-values can be noticed in cases 2 and 3, considerably diminishing solar gains, which could be both beneficial regarding cooling needs, but detrimental regarding the heating ones. Finally, it is worth mentioning that independently from the magnitudes, the distribution and proportions of the heat gains and losses are similar in the remaining simulated locations. 4. Conclusions The results show that the implementation of the NTM-11 standard would highly improve the energy performance of typical Chilean dwellings. The savings would depend on the dwelling’s geometry, materiality and design; but reductions from ~40% could be expected when using an appropriate approach regarding windows’ orientation and thermal mass, which were found to be especially determining in the warmer locations (Antofagasta and Santiago). Furthermore, since heating is the main concern along the country and cooling loads can be minimized using passive strategies, as the ones assessed, the efforts should be focused on further reducing the heat losses when aiming for low or nearly-zero energy performances. Based on the resulting energy balances in Santiago when complying with the NTM-11, several conclusions can be drawn when aiming to further improve housing energy performance. Since uninsulated floors-on-ground are the main cause of heat loss in the single-family cases, insulation seems to be needed. Walls remain as a considerable cause of heat loss despite the high reductions achieved by tightening its U-value. On the contrary, the roof limiting U-value seems appropriate at this stage. With regards to windows, limiting its proportion might be counterproductive when aiming to take advantage of solar gains, which were found to be highly relevant in this location, especially if solar control strategies are used to avoid overheating. In fact, the reduction of the glazing g-values was found to be effective in reducing the cooling loads, but shading devices, which were not assessed, could better help regulating seasonal solar access. The U-values, on the other hand, should be further reduced when aiming for better performances. Finally, since ventilation and air infiltrations were shown to be highly influential in the energy performance of dwellings along the country, further research should better weigh the limiting values for both air infiltrations and ventilation rates, in order to achieve both energy efficiency and air quality. Furthermore, high performance ventilation strategies, as heat recovery systems, should also be explored when aiming for nearly-zero energy buildings. Acknowledgements This review was undertaken as part of a doctoral study in the Building Physics Department of the Technische Universität Berlin, financed by a scholarship from the German Academic Exchange Office DAAD. References [1] Ministerio de Energía. Balance nacional de energía 2013. Santiago, 2014. Retrieved from Gobierno de Chile website: http://dataset.cne.cl/Energia_Abierta/Balances%20Energeticos/bne_2013.xls. (Accessed 16.01.2017) [2] Ministerio de Energía. Energy 2050: Chile’s Energy Policy. Santiago: Ministerio de Energía; 2015. [3] CDT. Estudio de usos finales y curva de oferta de conservación de la energía en el sector residencial de Chile. Santiago: Programa país de eficiencia energética; 2010. [4] Bustamante, W., Rozas, Y., Cepeda, R., Encinas, F., & Martinez, P. Guía de diseño para la eficiencia energética en la vivienda social. Santiago: MINVU & CNE; 2009. [5] OECD. OECD Economic Surveys: Chile 2012. Paris: OECD Publishing; 2012. http://dx.doi.org/10.1787/eco_surveys-chl-2012-en [6] Prestandard NTM 011:2014. Requisitos y mecanismos de acreditación para acondicionamiento ambiental de las edificaciones. Santiago: MINVU; 2014. [7] Prestandard DIN V 18599-2:2016-10 Energy efficiency of buildings – Calculation of the net, final and primary energy demand for heating, cooling, ventilation, domestic hot water and lighting – Part 2: Net energy demand for heating and cooling of building zones. Berlin: Beuth Verlag, 2016. [8] NCh3309:2014 Ventilation and acceptable indoor air quality in low-rise residential buildings. Santiago: INN; 2014.