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One detail that is especially beneficial to the thermal performance of a house is a modified, two-stud corner that allows more insulation and blocks much of the thermal bridging in a conventionally framed corner. With less cold air inside the wall cavity, the chance of condensation and mold declines. Adding a layer of insulating sheathing to the outside of the building is an added benefit. Drywall clips or an extra piece of 1 in. x 4 in. catches the edge of interior drywall.
Whether the house is new construction or a retrofit, local weather patterns are a basic planning tool for a zero energy home. Data should include precipitation records, average temperatures by month and preferably by day over the last several years. Local airports often keep detailed weather records, and a local college or university may be able to provide projections of weather patterns and the potential for regional climate change.
Energy in your home has to be designed as a system. Whether or not you think about it, your home is always interacting with the environment. Hot sunny days create one response from your home's cooling system; cold snowy days create a totally different response from your heating system. When you consciously question your environment (When does the sun rise? What rooms does the sun shine into and when? In what direction does the wind blow in different seasons?), you create design requirements that are more efficient than automated systems because they are in tune with your specific environment.
Does this scene sound familiar? A culture facing an environmental crisis. Their primary building resource — wood — was in high demand for ships and buildings, making the primary heat source for comfort — charcoal — increasingly scarce and expensive. This was the situation that faced the Greeks in the 5th century B.C.E. Most of the Greek peninsula and the islands had been denuded so they were forced to import wood from faraway places. This drove the ancient architects to reevaluate how they built their buildings.
Passive Solar and Zero Energy Homes
The marriage of passive solar design with zero energy homes makes cost-effective heating and cooling possible. Solar is simultaneously the first and last thought in a zero energy home. Orientation comes first, enabling the building to take the fullest advantage of the sun. The last thought is where and how much solar hot water and photovoltaics (PVs) to put on the building to make up the last of the loads that can't be provided by the design and operation of the home. The less solar equipment required, the more cost effective the construction costs of the home.
Getting to Zero
Passive solar design is much easier to apply in new buildings than in existing homes. Virtually every zero energy house in colder climates has taken full advantage of passive solar heating potential; up to 60% of the heating load can be met through passive solar design.