Designers of cost-effective zero-energy homes have been persuaded by recent advancements in building materials and processes to place less emphasis on full passive solar design than before. Variable climate conditions, higher costs of low U-value/high SHGC windows, the advantages of having fewer windows, and the high cost of thermal mass are all contributing considerations. Another is the danger of overheating if passive solar isn’t effectively handled. These are just a few. Instead of increasing window area or spending more money, solar tempering offers a more cost-effective option that makes use of solar heat gain. Most windows and the common living rooms should face south for this to operate well. The ideal amount of shade allows winter warmth to enter while keeping summer heat out. Heat and light are provided by solar tempering, which can reduce heating expenses by 10 to 20 percent without additional expense or risk of overheating in the summer.
During the design phase, incorporate the following components for successful solar tempering:
- If it’s feasible, choose windows with a greater Solar Heat Gain Coefficient (SHGC) on the south side, such as those with a SHGC of 0.4 or higher.
- In general, aim for a WFA of 14% for the entire house, with 50% of windows on the south side being used for the common living rooms. More south-facing windows may or may not be cost-effective depending on local conditions.
- Plan your shading so that you may take advantage of the winter light to your advantage while also providing summer shade for your south-facing windows. There will always be a trade-off in the length of a fixed overhang due to the sun’s constant angle from March to September. Reduce the length of overhangs, and then use outdoor shading like awnings or vegetation to block off unnecessary sunlight gain.
- During the design phase, determine the BTU gain from solar heating. Use energy modeling tools to determine these solar gains. Passive solar gains are included in the calculations of REM/Design, REM/Rate, EnergyPlus, and Energy10.
- Use Hunter-Douglas’ Duet Architella shades, which have an R-value of close to 4, to help keep out cold or heat depending on the season. These blinds are insulated. Homeowners must be willing to close them on chilly winter nights and scorching summer days so they may be fitted properly.
- Passive solar solutions cost a lot more money, but they don’t provide as much value as solar tempering.