The following provides design knowledge and resource location assistance for energy and resource efficient, environmentally-friendly, low-maintenance construction geared toward a warmer, southern climate.
Do the right things in the right order:
Passive Solar Design - These low or no-cost features can have a major impact in energy use. See the link to Passive Solar for additional info. Here's an additional guide to Passive Solar.
Structure and Insulation
- Find construction systems and techniques that result in superior energy performance and comfort. Consistent insulation and air-tight construction are the goals.
- Consider systems other than typical stud construction: Structural Insulated Panels (SIPS) and Insulated Concrete Forms ((ICFs) are two such systems.
- If you must use stud construction use 2x6 with icynene in the walls and an exterior insulation board to reduce stud conductivity.
- Consider eliminating the attic and using a cathedral ceiling. If you have an attic use proper ventilation. A continuous ridge vent system is best. The spinning wind ventilators also work well.
- Radiant Barrier - If you have good ventilation and proper insulation levels then consider installing a radiant barrier in the attic. Q&A sheet on radiant barrier. Then get an Energy Star or Cool Roof.
Windows and Doors - Use high-performance windows and doors. Energy Star link.
- Use at least double pane glazing with argon fill for a low U value.
- Specify spectrally selective low-E glazing.
- Use vinyl or fiberglass insulated frames.
- Look for low solar heat gain coefficient (SHGC) and high visible light transmission (VLT).
Heating, Ventilation, and Air Conditioning (HVAC) - If the first 3 steps above are done well you can install a much smaller (less expensive) unit. Correctly size the air conditioning unit.
- Consider Ground Source Heat Pump (GSHP) geothermal systems with a desuperheater for free hot water in the summer.
- Place ductwork in the conditioned space to reduce air and thermal losses (consider a home with no attic)
- If you build at tight home you can introduce controlled and conditioned fresh air with an Energy Recovery Ventilator (ERV).
Water Heating - Install solar water heaters, wastewater heat recovery, units that recover waste heat from the air conditioner, and a well-insulated tank.
- Purchase a well insulated water tank such as the Marathon.
- Consider a GFX recovery heat exchanger on second floor shower drains.
- For year round heating consider solar water heating
Lighting - Use fluorescent fixtures, compact fluorescent and LED bulbs (after designing for good daylight harvesting).
Appliances - Use energy efficient appliances and search out and eliminate phantom loads (vampire power).
- Check the Energy Star database to help select appliances.
- Use plug strips to turn off appliances that aren't in use. Consider an automatic Smart Strips to manage attached loads such as monitors and printers.
Water Conservation - Utilize landscape and interior conservation strategies combined with rain water collection and usage.
- Plant native or well-adapted drought tolerant trees, plants, and grasses - More Info
- Install efficient fixtures
- Consider capturing rainwater from the roof for outdoor uses or go for a whole house system.
Indoor Air Quality - Utilize systems and materials to keep dust, mold, allergens, and irritating chemicals at bay.
Recycled Materials - Use recycled building materials such as carpet made from recycled plastic and deck boards made from waste cedar shavings and recycled plastic.
Its difficult to generalize about an existing house because the weak points are different for every one. The first step is to locate your house weak points and attack those. The following information can act as a general guide. You can also hire a professional energy auditor to do a complete analysis of your home. See the RESNET page to help locate a certified rater for your area. In the DFW area contact Roger Taylor of DwellGreen.
Some other online tools are:
Home Energy Saver
Energy Efficiency and Renewable Energy Site
Home Energy Checklist Smarter House
RMI Home Energy Briefs
Here are some common issues and solutions:
Insulation and Infiltration - This is often a weak spot in older homes. First check attic insulation and add more if necessary. R-30 should be a minimum. It's difficult to add insulation to existing walls, but you can caulk and seal around windows, doors, outlets, and switches to reduce air infiltration. If your A/C unit and ductwork are in the attic check the integrity of the ductwork and insulation. Sealing and insulating the delivery system can improve the system performance.
Windows and Solar Gain - If your windows are old aluminum frame models that frequently sweat in winter it might be time to replace them. Check the recommendations for new windows at New House Design Tips for advice. If any of your existing windows are exposed to direct sunlight you can benefit from blocking the sun before it hits the glass. Overhangs, awnings, solar screens, and trees/shrubs are just a few ways to tackle the problem.
Roof and Attic Ventilation - Most attics suffer from poor ventilation. You need a high place for hot air to exist and an equally sized low place for cooler air to enter. Here are two good sources of information: info1, info2. If you are replacing your roof consider a reflective product. If it's also hail resistant you will receive a large discount on your homeowners insurance in Texas.
Radiant Barrier - If you have good ventilation and proper insulation levels then consider installing a radiant barrier in the attic. Q&A sheet on radiant barriers.
Lighting - Install LED bulbs wherever possible. Payback will be very quick and you'll reduce the amount of waste heat your air conditioner must remove. Most homes will save over $100/year by removing incandescent bulbs.
HVAC - Keep your unit cleaned and change the filter regularly. Wash the coils on the outdoor unit and shade it (without blocking airflow). If your A/C unit and ductwork are in the attic check the integrity of the ductwork and insulation. Sealing and insulating the delivery system can improve the system performance.
Water Heating - Make sure your water heater is well insulated. You can add an insulation jacket and pipe insulation. Periodically flush sediment from the bottom. Consider adding a timer to electric water heaters to help reduce standby losses.
Appliances - Use energy efficient appliances and seek and eliminate phantom loads.
- Check the Energy Star database to help select appliances
- Measure your appliance phantom loads with a meter like this.
- Use plug strips to turn off appliances that aren't in use. Consider an automatic Smart Strips to manage attached loads such as monitors and printers.
- Activate your computer power saving features. Screen saver don't save energy - let the monitor go to sleep.