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HVAC efficiency: Can filter selection reduce HVAC energy costs?
20
Feature
Filtration+Separation January/February 2007
HVAC efficiency:
Can filter selection reduce HVAC energy costs? I
n a society becoming more aware of the effects of energy consumption, Zoe Grainge takes a look at whether filter efficiency can go some way to ease the energy burden of HVAC systems.
The Heating Ventilation and Air Conditioning (HVAC) system of a building plays a huge part in the building’s overall energy consumption and the health and welfare of its occupants. According to the US Department of Energy, HVAC accounts for 40 to 60% of the energy used in US commercial and residential buildings.
further, ASHRAE, in conjunction with the American Institute of Architects (AIA) and other organizations, has developed Advanced Energy Design Guide for Small Office Buildings, which provides a “sensible approach” and all the tools needed to create energy-efficient office buildings of up to 20,000 square feet.
As prices soar and environmental pressures increase, it is wise to look to HVAC systems as a way of cutting down on energy consumption. Kent Peterson, President-Elect of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) says: “There are ample opportunities for building managers to save 30% of the energy consumed in most buildings today. ASHRAE, the [US] Department of Energy and the Environmental Protection Agency [EPA] are all working to help educate building owners and operators on methods to reduce building energy consumption.”
The EPA, in conjunction with stakeholders, developed the energy rating as a screening tool; it does not by itself explain why a building performs a certain way, or how to change the building’s performance. It does, however, help organizations assess performance and identify those buildings that offer the best opportunities for improvement and recognition.
Peterson adds: “The first step is for a building manager to assess the performance of their building. In the US, the EPA Energy Star program provides one method to determine building performance with their online Portfolio Manager benchmarking tool.” ASHRAE supplies technical information to engineers and other professionals. It also writes standards and guidelines in its field of expertise to guide industry in the delivery of goods and services to the public. Their Energy Standard for Buildings Except Low-Rise Residential Buildings, sets the minimum energy efficiency required by most building codes. To take the standard even
fs4401_pg20_23.indd 20
No rules, no standards, just maths? A HVAC system refers to the equipment, distribution network, and terminals that provide either collectively or individually the heating, ventilating, or air-conditioning processes to a building. In assessing the energy efficiency of a building, it is necessary to evaluate the efficiency of a HVAC system, and identify areas for improvement. Filtration equipment manufacturer SPX Air Filtration says there are no hard and fast rules for evaluating the efficiency of a system; it’s a matter of simple mathematics. Paul Sennett, senior vice president, business development and marketing, elaborates: “There is a direct correlation between pressure drop (resistance to air flow through a filter) and the energy that is consumed. In simple terms the fan moving the air has to work harder to get it
through the filter if its resistance (pressure drop) is higher. The simplest way to improve energy efficiency in a HVAC system is to reduce the pressure drop over the filters.” Sennett says that it is easy to change a filter to a lower pressure drop, the difficulty is selecting a filter with lower pressure drop, but the same efficiency (ability to capture particles). This is the job of the filter manufacturer; to design media and filters, which maintain the efficiency whilst improving the pressure drop. “No standards are in place for this because it is simple maths,” he continues. “The broader question is that of 'life cycle cost' [LCC]. It would be easy to select a filter which reduces the energy consumption, but if the cost of the filter is very high, the filter does not last as long and the disposal costs are also high, then the entire cost of the filter throughout its life, becomes unsustainable.” Assessing the calculation of LCC is the job of trade bodies such as Eurovent (in Europe) as well as companies. Sennett says energy is typically 80% of the cost of running an air conditioning system and filter costs represent less than 20%, so it is clear that improvements in energy consumption – even if the filter cost is higher – will almost certainly be economically sensible given this ratio.
Calculating LCC for the full picture Although the maths involved in assessing the efficiency of a filter in a HVAC system is fairly simple, the calculation of LCC can take some time, as it should include a full picture of the building’s costs. SPX
30/01/2007 15:54:12
Feature
Filtration+Separation January/February 2007
Air Filtration has developed a piece of software to help customers calculate the system’s energy consumption given different scenarios of filter choice. The software takes specific information from the customer, some assumptions from standard Western European commercial buildings and then models the options and selects the optimum solution for LCC. In the US, Dave Matela, CAFS, KimberlyClark Filtration Products, says: “To look at HVAC filters as energy conservation tools, it’s first important to understand that the cost of energy used by filters far outweighs the price of the filter itself. In fact, energy costs can be ten times the initial filter price for a standard pleated filter and four to five times the initial filter price for a higher efficiency final filter.” Kimberly-Clark provides an interactive online energy calculator for professionals interested in seeing how the energy consumption of their HVAC filters compares with other filters. Matela says switching to a filter with a lower airflow resistance is one of the easiest changes to make to reduce HVAC system energy costs. But he adds: “Alternatively, a building owner may look to improve indoor air quality by selecting a filter which provides higher filtration efficiency at the same airflow resistance as the original filter. Recent technology developments enable this opportunity.”
fs4401_pg20_23.indd 21
The Department of Energy (DOE) in the US recommends a number of software options for predicting LCC and the efficiency of a HVAC system. These options are mainly to be used in the design phase of a building, although some have a use for retrofitting HVAC upgrades. The DOE sponsors a Building Energy Software Tools Directory that lists a number of software tools for building design and simulation that are available from the government and industry. These include the DOE-2, an energy analysis software program that calculates the hour-by-hour energy use of a building, given detailed information on the building’s location, construction, operation, and HVAC systems. A number of Windows-based versions of DOE-2 are commercially available.
21
of the building before anyone can potentially breathe them), Class II Type B3 biological safety cabinets, hazardous chemicals and cold storage rooms.
Sustainability in the lab
The EPA has indicated that laboratories are consuming 5 to 10 times more energy per square foot than typical office buildings. The campus set an early fundamental goal to design a highly energy efficient laboratory building while providing a high standard of safety, health and comfort for the building occupants. The project set out to reduce cooling and heating loads through the use of energy efficiency glazing, efficient lighting, and the effective use of daylight. Also, enough space and shaft locations were to be provided to design efficient supply and exhaust ducting with minimal fittings.
The US Green Building Council promotes the work of projects around the country to improve energy efficiency. The organisation points towards a recent award winning project at a university in California, where the HVAC system was central to the upgrade. The project won a sustainability award in California for the energy efficient features in the building. This project was a 95,000 gross square feet science building at California State University, which housed a number of laboratories. The laboratories included over 150 fume hoods (devices designed to keep hazardous fumes out of the room air by exhausting them out
The project included numerous energy efficiency features used for the HVAC systems. The feature of manifolded variable air volume made use of the four variable air volume air handling units supplying air conditioned air to the building. Each unit had two separate cooling coils to provide two separate cold decks from each unit. One cold duct from each unit supplies the chemistry labs. The configuration allowed the supply ducts serving the Chemistry labs to operate at a higher supply air temperature since they required more ventilation airflow due to the relative high quantity of fume hoods in these
30/01/2007 15:54:18
22
Feature
labs. This resulted in reduced cooling loads and reheat requirements. A whole-building approach was adopted to reduce cooling loads further by designing a highly efficient building envelope (doors, windows and walls) and lighting system. Heat from high wattage laboratory equipment was grouped when appropriate and exhausted to minimize impact on space cooling loads. Occupancy sensors were used in the office spaces to reduce cooling requirements when unoccupied. Fume hood zone presence sensors were used to lower fume hood face velocity to 60 fpm (feet per minute) when nothing was in front of fume hood. And airflow was cascaded from the offices as make-up air to the laboratories to reduce airflow, cooling and reheat requirements. Other features included Low-Pressure Drop Design, Right-Sizing Equipment, whereby the additional cost of energy monitoring and state-of-the-art laboratory controls systems was offset with the capital cost savings of right-sizing the HVAC equipment and corresponding electrical systems. A 70% airflow diversity factor was used for sizing the variable volume exhaust fans and supply air systems. System monitoring since occupancy has shown that the building now operates with an airflow diversity of 50-60%. Direct digital control and utility metering was also a feature – recommended by most HVAC equipment manufacturers as a vital addition to the process.
Building green The Green Building Council says the campus has been recording operating data and energy usage in the building since initial occupancy. It says: “The laboratory building is using less energy (161 British Thermal Units (BTU)/sfyr) than some of the other non-laboratory buildings on campus. We still believe there is flexibility in the design to optimize control strategies now that the building is fully occupied. The campus has begun a retrocommissioning project to retro-commission the mechanical systems utilizing the historical trend data collected. We believe this provides the opportunity for the control strategies to be further optimized to minimize cooling and reheat loads in the building.” Most organisations recommend a series of generic ‘tips’ for the operation of a HVAC system, that encourage best practice and good maintenance before significant funds are spent on upgrades. UK business Efficient Air says something as basic as assessing existing air change rates against minimum fresh air supply rates may provide an opportunity to significantly reduce supply and extract fan motor input power, and potentially heating and cooling load costs when installed in an Air Handling Unit. “Payback would be within 6 to 24 months,” the company says.
fs4401_pg20_23.indd 22
Filtration+Separation January/February 2007
It also recommends good practice benchmarks: “Measuring your existing systems performance and comparing with published best practice guides to identify worst offending systems for improvement as a monitoring and targeting exercise,” the company says. UK-based utility company National Grid has advice for its US customers on general monitoring of a building’s energy consumption: “Install paddle fans, stratotherm fans, or other re-circulating systems to create air movement,” the company says. “Ceiling temperatures can often be 30° to 40°C higher than floor temperatures, and air movement from fans can enhance the cooling ability of air conditioning systems. “Install time clocks, set-back thermostats, and microprocessor thermostats to monitor HVAC systems when buildings are unoccupied.” ASHRAE lists fifteen tips for operating a HVAC system efficiently: • Adjust workplace schedules to reduce energy use during the hours when there is most demand for electricity. If employees start work earlier or have lunch during the hottest hour of the day, a company can save on air conditioning, lighting and other electricity use during the hours of peak electricity demand. • Prevent solar entry and air-conditioning loss during the summer. Use shades and blinds to keep the sun out. Close doors to the outside to keep in cooler air. Perform regular maintenance to keep HVAC systems running more efficiently. Maintenance activities can save up to 30% of fan energy and up to 10% of space conditioning energy use. • Occupancy sensors can be used to turn off lighting and change zone temperature setpoints when spaces are unoccupied. • Reduce air conditioning and heating hours by installing a time clock to turn off the system when the building is unoccupied. • Perform regular maintenance on cooling equipment. Regularly clean condenser coils, change belts and filters and fix duct leaks. Also check for proper economizer operation and adequate refrigerant levels. Maintenance activities can save up to 30% of fan energy and up to 10% of space conditioning energy use. • Add controls to the exhaust fan. Ask an air conditioning contractor to install timers and switches to shut them off when they are not needed, such as when the building is unoccupied. • Perform regular maintenance on heating equipment. Inspect and patch leaky heating ducts. Fix steam leaks. Clean blower coils and heat exchanger surfaces.
Adjust belt drives, dampers, valves and linkages. • For US businesses, install an Energy Star programmable thermostat to automate the HVAC system. An “old-fashioned” thermostat turns the HVAC on and off based on temperature, not whether the building is occupied, or whether users benefit from the cooling/heating. A programmable thermostat can optimize HVAC operation 24/7. For example, instead of heating or cooling all night, so users can enter a comfortable building in the morning, this “smart thermostat” can turn on the HVAC one hour before users arrive, based on their daily/hourly needs. • Install a high efficiency HVAC system. • Install an energy management system (EMS), and save 30 – 40% on annual investment. An EMS is especially useful when the air conditioning system is too complex to control with time clocks or programmable thermostats. An EMS lets users choose different cooling temperatures for different zones, optimum equipment start and stop times and control strategies that keep building occupants comfortable while minimizing energy use. • Consider installing variable frequency drives (VFDs), and save 30 – 40% on annual investment. Air conditioning system has fans that move air throughout the building. It is possible to reduce the cost of operating these fans by installing VFDs, which can change the speed of the fan motors to match the amount of air that is needed. • When fan and pump motors need repair, consider replacing them with premium efficiency models, and save 35 to 45% on annual investment. • Pressurize and test all ducts for leakage. • Install utility meters to track HVAC energy consumption
Be holistic Although it is important to assess the equipment efficiency within the HVAC system itself, it is clear that the system cannot be viewed in isolation from other – perhaps design-oriented elements – of a building’s energy efficiency and consumption rate. It is not always possible to address the issue of energy efficiency at the schematic design stage in a building’s life, but as can be seen from the award winning example at California State University, taking a holistic approach to a system in need of an upgrade can work. As the US DOE puts it: “The best HVAC design considers all the interrelated building systems while addressing indoor air quality, energy consumption, and environmental benefit.”
•
30/01/2007 15:54:19
Feature
Filtration+Separation January/February 2007
HVAC efficiency:
Can filter selection reduce HVAC energy costs? I
n a society becoming more aware of the effects of energy consumption, Zoe Grainge takes a look at whether filter efficiency can go some way to ease the energy burden of HVAC systems.
The Heating Ventilation and Air Conditioning (HVAC) system of a building plays a huge part in the building’s overall energy consumption and the health and welfare of its occupants. According to the US Department of Energy, HVAC accounts for 40 to 60% of the energy used in US commercial and residential buildings.
further, ASHRAE, in conjunction with the American Institute of Architects (AIA) and other organizations, has developed Advanced Energy Design Guide for Small Office Buildings, which provides a “sensible approach” and all the tools needed to create energy-efficient office buildings of up to 20,000 square feet.
As prices soar and environmental pressures increase, it is wise to look to HVAC systems as a way of cutting down on energy consumption. Kent Peterson, President-Elect of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) says: “There are ample opportunities for building managers to save 30% of the energy consumed in most buildings today. ASHRAE, the [US] Department of Energy and the Environmental Protection Agency [EPA] are all working to help educate building owners and operators on methods to reduce building energy consumption.”
The EPA, in conjunction with stakeholders, developed the energy rating as a screening tool; it does not by itself explain why a building performs a certain way, or how to change the building’s performance. It does, however, help organizations assess performance and identify those buildings that offer the best opportunities for improvement and recognition.
Peterson adds: “The first step is for a building manager to assess the performance of their building. In the US, the EPA Energy Star program provides one method to determine building performance with their online Portfolio Manager benchmarking tool.” ASHRAE supplies technical information to engineers and other professionals. It also writes standards and guidelines in its field of expertise to guide industry in the delivery of goods and services to the public. Their Energy Standard for Buildings Except Low-Rise Residential Buildings, sets the minimum energy efficiency required by most building codes. To take the standard even
fs4401_pg20_23.indd 20
No rules, no standards, just maths? A HVAC system refers to the equipment, distribution network, and terminals that provide either collectively or individually the heating, ventilating, or air-conditioning processes to a building. In assessing the energy efficiency of a building, it is necessary to evaluate the efficiency of a HVAC system, and identify areas for improvement. Filtration equipment manufacturer SPX Air Filtration says there are no hard and fast rules for evaluating the efficiency of a system; it’s a matter of simple mathematics. Paul Sennett, senior vice president, business development and marketing, elaborates: “There is a direct correlation between pressure drop (resistance to air flow through a filter) and the energy that is consumed. In simple terms the fan moving the air has to work harder to get it
through the filter if its resistance (pressure drop) is higher. The simplest way to improve energy efficiency in a HVAC system is to reduce the pressure drop over the filters.” Sennett says that it is easy to change a filter to a lower pressure drop, the difficulty is selecting a filter with lower pressure drop, but the same efficiency (ability to capture particles). This is the job of the filter manufacturer; to design media and filters, which maintain the efficiency whilst improving the pressure drop. “No standards are in place for this because it is simple maths,” he continues. “The broader question is that of 'life cycle cost' [LCC]. It would be easy to select a filter which reduces the energy consumption, but if the cost of the filter is very high, the filter does not last as long and the disposal costs are also high, then the entire cost of the filter throughout its life, becomes unsustainable.” Assessing the calculation of LCC is the job of trade bodies such as Eurovent (in Europe) as well as companies. Sennett says energy is typically 80% of the cost of running an air conditioning system and filter costs represent less than 20%, so it is clear that improvements in energy consumption – even if the filter cost is higher – will almost certainly be economically sensible given this ratio.
Calculating LCC for the full picture Although the maths involved in assessing the efficiency of a filter in a HVAC system is fairly simple, the calculation of LCC can take some time, as it should include a full picture of the building’s costs. SPX
30/01/2007 15:54:12
Feature
Filtration+Separation January/February 2007
Air Filtration has developed a piece of software to help customers calculate the system’s energy consumption given different scenarios of filter choice. The software takes specific information from the customer, some assumptions from standard Western European commercial buildings and then models the options and selects the optimum solution for LCC. In the US, Dave Matela, CAFS, KimberlyClark Filtration Products, says: “To look at HVAC filters as energy conservation tools, it’s first important to understand that the cost of energy used by filters far outweighs the price of the filter itself. In fact, energy costs can be ten times the initial filter price for a standard pleated filter and four to five times the initial filter price for a higher efficiency final filter.” Kimberly-Clark provides an interactive online energy calculator for professionals interested in seeing how the energy consumption of their HVAC filters compares with other filters. Matela says switching to a filter with a lower airflow resistance is one of the easiest changes to make to reduce HVAC system energy costs. But he adds: “Alternatively, a building owner may look to improve indoor air quality by selecting a filter which provides higher filtration efficiency at the same airflow resistance as the original filter. Recent technology developments enable this opportunity.”
fs4401_pg20_23.indd 21
The Department of Energy (DOE) in the US recommends a number of software options for predicting LCC and the efficiency of a HVAC system. These options are mainly to be used in the design phase of a building, although some have a use for retrofitting HVAC upgrades. The DOE sponsors a Building Energy Software Tools Directory that lists a number of software tools for building design and simulation that are available from the government and industry. These include the DOE-2, an energy analysis software program that calculates the hour-by-hour energy use of a building, given detailed information on the building’s location, construction, operation, and HVAC systems. A number of Windows-based versions of DOE-2 are commercially available.
21
of the building before anyone can potentially breathe them), Class II Type B3 biological safety cabinets, hazardous chemicals and cold storage rooms.
Sustainability in the lab
The EPA has indicated that laboratories are consuming 5 to 10 times more energy per square foot than typical office buildings. The campus set an early fundamental goal to design a highly energy efficient laboratory building while providing a high standard of safety, health and comfort for the building occupants. The project set out to reduce cooling and heating loads through the use of energy efficiency glazing, efficient lighting, and the effective use of daylight. Also, enough space and shaft locations were to be provided to design efficient supply and exhaust ducting with minimal fittings.
The US Green Building Council promotes the work of projects around the country to improve energy efficiency. The organisation points towards a recent award winning project at a university in California, where the HVAC system was central to the upgrade. The project won a sustainability award in California for the energy efficient features in the building. This project was a 95,000 gross square feet science building at California State University, which housed a number of laboratories. The laboratories included over 150 fume hoods (devices designed to keep hazardous fumes out of the room air by exhausting them out
The project included numerous energy efficiency features used for the HVAC systems. The feature of manifolded variable air volume made use of the four variable air volume air handling units supplying air conditioned air to the building. Each unit had two separate cooling coils to provide two separate cold decks from each unit. One cold duct from each unit supplies the chemistry labs. The configuration allowed the supply ducts serving the Chemistry labs to operate at a higher supply air temperature since they required more ventilation airflow due to the relative high quantity of fume hoods in these
30/01/2007 15:54:18
22
Feature
labs. This resulted in reduced cooling loads and reheat requirements. A whole-building approach was adopted to reduce cooling loads further by designing a highly efficient building envelope (doors, windows and walls) and lighting system. Heat from high wattage laboratory equipment was grouped when appropriate and exhausted to minimize impact on space cooling loads. Occupancy sensors were used in the office spaces to reduce cooling requirements when unoccupied. Fume hood zone presence sensors were used to lower fume hood face velocity to 60 fpm (feet per minute) when nothing was in front of fume hood. And airflow was cascaded from the offices as make-up air to the laboratories to reduce airflow, cooling and reheat requirements. Other features included Low-Pressure Drop Design, Right-Sizing Equipment, whereby the additional cost of energy monitoring and state-of-the-art laboratory controls systems was offset with the capital cost savings of right-sizing the HVAC equipment and corresponding electrical systems. A 70% airflow diversity factor was used for sizing the variable volume exhaust fans and supply air systems. System monitoring since occupancy has shown that the building now operates with an airflow diversity of 50-60%. Direct digital control and utility metering was also a feature – recommended by most HVAC equipment manufacturers as a vital addition to the process.
Building green The Green Building Council says the campus has been recording operating data and energy usage in the building since initial occupancy. It says: “The laboratory building is using less energy (161 British Thermal Units (BTU)/sfyr) than some of the other non-laboratory buildings on campus. We still believe there is flexibility in the design to optimize control strategies now that the building is fully occupied. The campus has begun a retrocommissioning project to retro-commission the mechanical systems utilizing the historical trend data collected. We believe this provides the opportunity for the control strategies to be further optimized to minimize cooling and reheat loads in the building.” Most organisations recommend a series of generic ‘tips’ for the operation of a HVAC system, that encourage best practice and good maintenance before significant funds are spent on upgrades. UK business Efficient Air says something as basic as assessing existing air change rates against minimum fresh air supply rates may provide an opportunity to significantly reduce supply and extract fan motor input power, and potentially heating and cooling load costs when installed in an Air Handling Unit. “Payback would be within 6 to 24 months,” the company says.
fs4401_pg20_23.indd 22
Filtration+Separation January/February 2007
It also recommends good practice benchmarks: “Measuring your existing systems performance and comparing with published best practice guides to identify worst offending systems for improvement as a monitoring and targeting exercise,” the company says. UK-based utility company National Grid has advice for its US customers on general monitoring of a building’s energy consumption: “Install paddle fans, stratotherm fans, or other re-circulating systems to create air movement,” the company says. “Ceiling temperatures can often be 30° to 40°C higher than floor temperatures, and air movement from fans can enhance the cooling ability of air conditioning systems. “Install time clocks, set-back thermostats, and microprocessor thermostats to monitor HVAC systems when buildings are unoccupied.” ASHRAE lists fifteen tips for operating a HVAC system efficiently: • Adjust workplace schedules to reduce energy use during the hours when there is most demand for electricity. If employees start work earlier or have lunch during the hottest hour of the day, a company can save on air conditioning, lighting and other electricity use during the hours of peak electricity demand. • Prevent solar entry and air-conditioning loss during the summer. Use shades and blinds to keep the sun out. Close doors to the outside to keep in cooler air. Perform regular maintenance to keep HVAC systems running more efficiently. Maintenance activities can save up to 30% of fan energy and up to 10% of space conditioning energy use. • Occupancy sensors can be used to turn off lighting and change zone temperature setpoints when spaces are unoccupied. • Reduce air conditioning and heating hours by installing a time clock to turn off the system when the building is unoccupied. • Perform regular maintenance on cooling equipment. Regularly clean condenser coils, change belts and filters and fix duct leaks. Also check for proper economizer operation and adequate refrigerant levels. Maintenance activities can save up to 30% of fan energy and up to 10% of space conditioning energy use. • Add controls to the exhaust fan. Ask an air conditioning contractor to install timers and switches to shut them off when they are not needed, such as when the building is unoccupied. • Perform regular maintenance on heating equipment. Inspect and patch leaky heating ducts. Fix steam leaks. Clean blower coils and heat exchanger surfaces.
Adjust belt drives, dampers, valves and linkages. • For US businesses, install an Energy Star programmable thermostat to automate the HVAC system. An “old-fashioned” thermostat turns the HVAC on and off based on temperature, not whether the building is occupied, or whether users benefit from the cooling/heating. A programmable thermostat can optimize HVAC operation 24/7. For example, instead of heating or cooling all night, so users can enter a comfortable building in the morning, this “smart thermostat” can turn on the HVAC one hour before users arrive, based on their daily/hourly needs. • Install a high efficiency HVAC system. • Install an energy management system (EMS), and save 30 – 40% on annual investment. An EMS is especially useful when the air conditioning system is too complex to control with time clocks or programmable thermostats. An EMS lets users choose different cooling temperatures for different zones, optimum equipment start and stop times and control strategies that keep building occupants comfortable while minimizing energy use. • Consider installing variable frequency drives (VFDs), and save 30 – 40% on annual investment. Air conditioning system has fans that move air throughout the building. It is possible to reduce the cost of operating these fans by installing VFDs, which can change the speed of the fan motors to match the amount of air that is needed. • When fan and pump motors need repair, consider replacing them with premium efficiency models, and save 35 to 45% on annual investment. • Pressurize and test all ducts for leakage. • Install utility meters to track HVAC energy consumption
Be holistic Although it is important to assess the equipment efficiency within the HVAC system itself, it is clear that the system cannot be viewed in isolation from other – perhaps design-oriented elements – of a building’s energy efficiency and consumption rate. It is not always possible to address the issue of energy efficiency at the schematic design stage in a building’s life, but as can be seen from the award winning example at California State University, taking a holistic approach to a system in need of an upgrade can work. As the US DOE puts it: “The best HVAC design considers all the interrelated building systems while addressing indoor air quality, energy consumption, and environmental benefit.”
•
30/01/2007 15:54:19