The Louisiana Solar Energy Society is an
educational organization formed to promote the
use of solar energy and to share information
on the subject between its members and the

Home Links LA Solar Pro/Sponsors Join Contact Us



Energy Savings Tips

                From the Florida Solar Energy Center:  Here's what is most important:. 
                                 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. 
                                 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. Unshaded 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. 
                                 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). 
                                 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. 
                                 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 (oF) which the house is cooled 
                                 below 80 oF increases annual cooling by 12%! 
                                 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 Manual J. 
                                 Room AC should be at least EER 10.0. 
                                 Interior duct system Install ductwork inside conditioned 
                                 envelope. Seal and test duct system. Maximum tested 
                                 leakage should be 25 CFM/1000 sqft of conditioned floor area 
                                 at a 50 Pa test pressure. Insulate ductwork installed in 
                                 attics with R-8 or better. 
                                 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 
                                 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. 
                                 Central AC indoor unit should not be installed in the 
                                 attic. Garage or indoor only. 
                                 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 sqft system for a household of 
                                 two or three may be ideal. 
                                 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. 
                                 Wall insulation is a low priority. Same for low thermal 
                                 conductivity windows. Major advantage is allowing smaller 
                                 calculated AC systems when sized by Manual J. . 
                                 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. 
                                 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 Florida homes have shown 
                                 typical natural ventilation rates for sealed homes of no 
                                 greater than 0.2 ACH. 
                                 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 filte 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. 

                        Existing Buildings 

                        1. Light exterior surfaces (walls) when repainting or re-roofing. Light colored shingles. 

                        2. Improve attic thermal performance. Without a white roof, consider R-30 ceiling 
                        insulation with a truss mounted radiant barrier and better attic ventilation (soffit and ridge 

                        3. Sealed and tested duct system. Very important 

                        4. 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%.