Energy Savings Tips
Here's what is most important:
1. Proper window orientation. Windows should be maximized on north and south and minimized on east and particularly on the west and northwest. For instance, if a large fixed window will face west in a plan (nice view etc.), it is vital that it receive an effective awning, very wide overhang or porch or other treatment to reduce solar gain.
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2. Window Shading. Design building so windows are naturally shaded by porches, awnings, shutters, trellises. A wide porch is preferred on the south side of the home. This
reduces cost while preserving daylight and adding a very useful area to the home where shaded outdoor activities can occur. At least 3 ft overhangs should be provided around the perimeter of the building and 4 ft is preferable. First floor windows on two story buildings should receive particular attention. Un-shaded windows should have windows with a maximum shading coefficient of 0.6 installed. Spectrally selective types are preferred, but expensive (>$10/ft2 installed). Trees can be very effective and increase home value as they grow.
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3. Light colored surfaces. Recommended for all of building exterior (this has a large impact on annual cooling; it is low cost since materials and colors are discretionary and color has little impact on cost). R-19 insulation is adequate in hot climates if the roof is white. Best white roof will be a pitched metal galvalum type which will maintain its reflectance and space cooling by 10% over other options. If a white roof is not specified then adequate attic ventilation (gable/ridge and soffit) should be provided with at least R-30 ceiling insulation and a truss mounted radiant barrier system (RBS).
Although they do not provide the performance advantage of a true white roof, light colored shingles (light gray or white) are still preferred although an RBS, added insulation, and good attic ventilation is recommended. Knee-wall insulation in cathedral ceilings should be carefully attached (standard practice falls off of vertical sections). (Attic fans)
1. Proper window orientation. Windows should be maximized on north and south and minimized on east and particularly on the west and northwest. For instance, if a large fixed window will face west in a plan (nice view etc.), it is vital that it receive an effective awning, very wide overhang or porch or other treatment to reduce solar gain.
.
2. Window Shading. Design building so windows are naturally shaded by porches, awnings, shutters, trellises. A wide porch is preferred on the south side of the home. This
reduces cost while preserving daylight and adding a very useful area to the home where shaded outdoor activities can occur. At least 3 ft overhangs should be provided around the perimeter of the building and 4 ft is preferable. First floor windows on two story buildings should receive particular attention. Un-shaded windows should have windows with a maximum shading coefficient of 0.6 installed. Spectrally selective types are preferred, but expensive (>$10/ft2 installed). Trees can be very effective and increase home value as they grow.
.
3. Light colored surfaces. Recommended for all of building exterior (this has a large impact on annual cooling; it is low cost since materials and colors are discretionary and color has little impact on cost). R-19 insulation is adequate in hot climates if the roof is white. Best white roof will be a pitched metal galvalum type which will maintain its reflectance and space cooling by 10% over other options. If a white roof is not specified then adequate attic ventilation (gable/ridge and soffit) should be provided with at least R-30 ceiling insulation and a truss mounted radiant barrier system (RBS).
Although they do not provide the performance advantage of a true white roof, light colored shingles (light gray or white) are still preferred although an RBS, added insulation, and good attic ventilation is recommended. Knee-wall insulation in cathedral ceilings should be carefully attached (standard practice falls off of vertical sections). (Attic fans)
.
4. Low energy use appliances and lighting. To reduce internal loads. Generally, each three kWh of energy saved within the home will reduce the need for mechanical cooling
by an additional kWh. An efficient refrigerator is particularly important in this regard since all heat is released internally and they operate year round. Insist on a more efficient
model from the Energy Guide label. And remember, that the old, used refrigerator in the garage is probably costing $175 or more per year in energy to operate. Compact fluorescent lamps (CFLs) reduce electricity consumption for lighting and byproduct heat. Use CFLs for recessed cans, kitchens and outdoor fixtures. (You may also use LED, occupancy sensors and photo-cell for outside lighting)
.
5. Digital programmable thermostat. For those who will use it. Otherwise, use a digital non-programmable thermostat with battery back-up. These provide accurate setting for
occupants. Each degree which the house is cooled below 80 degrees increases annual cooling by 12%!
.
6. High SEER AC. Purchase new air conditioning units with a Seasonal Energy Efficiency Ratio (SEER) of at least 14 Btu/W. Variable speed indoor fan units should be specified if possible. Unit should be sized using Manual J with the 97.5% summer design temperature for the location and a 75 F indoor temperature. Where windows coverings are unknown, blinds should be assumed for the calculations. The AC unit chosen should be closest to that indicated by code. Room AC should be at least EER 10.0.
.
7. Interior duct system Install ductwork inside conditioned envelope. Seal and test duct system. Maximum tested leakage should be 25 CFM/1000 sq ft of conditioned floor area
at a 50 Pa test pressure. Insulate ductwork installed in attics with R-8 or better.
8. Low friction loss duct system. Design duct system for 0.05 IWC/100 ft of equivalent length (duct slide rules dominate industry); low duct friction loss will improve EER by up to 12%.
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9. AC blower tested (with return grill mounted balometer). To provide at least 375 cfm per ton of capacity at time of installation (very important). Fan speed settings should be
altered to achieve this target at time of install.
.
10. Central AC indoor unit should not be installed in the attic. Garage or indoor only. (You may consider installing a geothermal HVAC system).
.
11. Solar Water Heating. A modest sized solar water heating system will provide 50-70% of an average household's hot water needs at low cost. Consider systems with collectors of 40 square feet or less. A 24 sq ft system for a household of two or three may be ideal.
.
12. Cross ventilation area should be promoted. Prefer fully open-able windows: awning or casement types. Single, double hung and fixed windows are progressively less helpful. Whole house fans may be very useful, but their nighttime use may lead to prohibitively high interior humidity levels. Look into humidifiers in winter and de-humidifiers in summer and ERV system.
.
13. Wall insulation is a low priority. Same for low thermal conductivity windows. Major advantage is allowing smaller calculated AC systems when sized by code.
.
14. Ceiling fans should be specified with wall switches (rather than chain operated controls) to promote turning fans off when leaving the room. Ideally, fan blades should be mounted with 9" or more air space above them. Use large blade fans for large rooms.
.
15. Greater weatherization not recommended because of already low natural air change rates in hot climate buildings (little stack or wind to drive infiltration). Testing using SF6
tracer gas in a large sample of West coast homes have shown typical natural ventilation rates for sealed homes of no greater than 0.2 ACH.
.
16. Swimming pools. If you have one, pumping costs easily comprise 20% of total electricity use. One very cost effective way to reduce this expense in new construction is
to use an oversized cartridge filter and 2" PVC piping rather than the standard 1/2" inch. Then locate a pump no larger than 1/2 hp per 10,000 gallons of pool volume. Set the pump on a timer to operate no more than six hours per day in summer and three hours in winter. If heating a pool, use a cover and a solar pool heating system.
4. Low energy use appliances and lighting. To reduce internal loads. Generally, each three kWh of energy saved within the home will reduce the need for mechanical cooling
by an additional kWh. An efficient refrigerator is particularly important in this regard since all heat is released internally and they operate year round. Insist on a more efficient
model from the Energy Guide label. And remember, that the old, used refrigerator in the garage is probably costing $175 or more per year in energy to operate. Compact fluorescent lamps (CFLs) reduce electricity consumption for lighting and byproduct heat. Use CFLs for recessed cans, kitchens and outdoor fixtures. (You may also use LED, occupancy sensors and photo-cell for outside lighting)
.
5. Digital programmable thermostat. For those who will use it. Otherwise, use a digital non-programmable thermostat with battery back-up. These provide accurate setting for
occupants. Each degree which the house is cooled below 80 degrees increases annual cooling by 12%!
.
6. High SEER AC. Purchase new air conditioning units with a Seasonal Energy Efficiency Ratio (SEER) of at least 14 Btu/W. Variable speed indoor fan units should be specified if possible. Unit should be sized using Manual J with the 97.5% summer design temperature for the location and a 75 F indoor temperature. Where windows coverings are unknown, blinds should be assumed for the calculations. The AC unit chosen should be closest to that indicated by code. Room AC should be at least EER 10.0.
.
7. Interior duct system Install ductwork inside conditioned envelope. Seal and test duct system. Maximum tested leakage should be 25 CFM/1000 sq ft of conditioned floor area
at a 50 Pa test pressure. Insulate ductwork installed in attics with R-8 or better.
8. Low friction loss duct system. Design duct system for 0.05 IWC/100 ft of equivalent length (duct slide rules dominate industry); low duct friction loss will improve EER by up to 12%.
.
9. AC blower tested (with return grill mounted balometer). To provide at least 375 cfm per ton of capacity at time of installation (very important). Fan speed settings should be
altered to achieve this target at time of install.
.
10. Central AC indoor unit should not be installed in the attic. Garage or indoor only. (You may consider installing a geothermal HVAC system).
.
11. Solar Water Heating. A modest sized solar water heating system will provide 50-70% of an average household's hot water needs at low cost. Consider systems with collectors of 40 square feet or less. A 24 sq ft system for a household of two or three may be ideal.
.
12. Cross ventilation area should be promoted. Prefer fully open-able windows: awning or casement types. Single, double hung and fixed windows are progressively less helpful. Whole house fans may be very useful, but their nighttime use may lead to prohibitively high interior humidity levels. Look into humidifiers in winter and de-humidifiers in summer and ERV system.
.
13. Wall insulation is a low priority. Same for low thermal conductivity windows. Major advantage is allowing smaller calculated AC systems when sized by code.
.
14. Ceiling fans should be specified with wall switches (rather than chain operated controls) to promote turning fans off when leaving the room. Ideally, fan blades should be mounted with 9" or more air space above them. Use large blade fans for large rooms.
.
15. Greater weatherization not recommended because of already low natural air change rates in hot climate buildings (little stack or wind to drive infiltration). Testing using SF6
tracer gas in a large sample of West coast homes have shown typical natural ventilation rates for sealed homes of no greater than 0.2 ACH.
.
16. Swimming pools. If you have one, pumping costs easily comprise 20% of total electricity use. One very cost effective way to reduce this expense in new construction is
to use an oversized cartridge filter and 2" PVC piping rather than the standard 1/2" inch. Then locate a pump no larger than 1/2 hp per 10,000 gallons of pool volume. Set the pump on a timer to operate no more than six hours per day in summer and three hours in winter. If heating a pool, use a cover and a solar pool heating system.
17. Harvesting and utilizing rainwater.
18. Utilizing grey-water for landscaping
Existing Buildings
A. Light exterior surfaces (walls) when repainting or re-roofing. B. Light colored shingles.
C. Improve attic thermal performance. Without a white roof, consider R-30
D. Ceiling insulation with a truss mounted radiant barrier and better attic ventilation (soffit and ridge vents).
E. Sealed and tested duct system. Very important
All of the above are applicable except for (1), (7), (8) and (16) which are not feasible.
Whole house fans may be useful for poor cross ventilation. Window films and retrofit
awnings and shading devices may be needed for problem windows. An appropriate window film will have a shading coefficient no more than 0.55 and a visible light transmittance of at least 50%.
Whole house fans may be useful for poor cross ventilation. Window films and retrofit
awnings and shading devices may be needed for problem windows. An appropriate window film will have a shading coefficient no more than 0.55 and a visible light transmittance of at least 50%.
F. the use of skylights and trees to block the sun during summer.
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