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
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.
1. Light exterior surfaces (walls) when repainting or re-roofing. Light
2. Improve attic thermal performance. Without a white roof, consider R-30
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
awnings and shading devices may be needed for problem windows. An appropriate
film will have a shading coefficient no more than 0.55 and a visible light
at least 50%.