I'm considering building a home with straw insulation and stucco. Can it be done in NY, where temps reach below zero with wind chill?
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We're thinking of a Spanish-style home, heated concrete floors, no ductwork. We want to power the home with wind turbines. Again, with wind the winter temps can reach below zero, and summer temps can reach about 95 here.
Strawbale construction is best suited for dry climates, but strawbale construction can be utilized in any area where straw is readily available. With New York’s rich agricultural diversity you should be able to find bales ranging in cost from $1 to $4.
Currently there are 16 homes listed on the Strawbale Building Registry in the state of New York. This type of construction works well with renewable energy resources and passive heating and cooling systems. The main reason for this is that strawbale walls, depending on the thickness, will typically range between R-35 and R-50.
There are two items of primary importance when considering strawbale construction:
- Tightness -- the density of a bale should be between 7 and 8 pounds/foot cubed. Anything less will allow for larger air spaces and a loss in thermal performance.
- Moisture -- the moisture content should not exceed 20%. Anything higher will contribute to mold, mildew and decomposition inside the wall cavity. It is recommended that the bales be tested with a moisture meter as they are installed to assure the highest quality and performance.
- It is important that the bales be consistent in size and shape. Inconsistency of size and shape will make leveling extremely difficult.
- Use long-stalk bales vs. chopped bales. Long-stalks are stronger than chopped strawbales.
- Do not use bales with grains attached. This is a food source for pests such as insects and rodents.
- Some bales have been treated for pests. Ask your supplier if you are concerned about possible pesticides.
- If plumbing and electrical runs are to be within the strawbales themselves, they will be required to be encased in a sleeve(s).
Next consideration is the power source. You had mentioned turbines for your electric generation. Make sure that all local codes and ordinances allow the use of wind turbines.
For optimum performance, a horizontal-oriented turbine should be mounted 30 feet above the nearest obstruction within a 250-foot radius. Vertical turbines work best in unstable winds, but will only produce on average 1-2 KW annually.
What I would suggest is the installation of a hybrid system. Look at incorporating amorphous photovoltaic panels with a wind turbine. Also, with a super-insulated home such as a strawbale home, I would consider the installation of a solar hot water heating system. A properly designed evacuated-tube solar hot water heating system can supply all of the domestic hot water as well as hot water for in-floor heating. Depending on the location of the home, passive cooling may be implemented.
However, if this is not feasible, you will need a separate cooling system. Consider the installation of a geothermal system for both heating and cooling. A geothermal unit, if equipped with a heat recovery unit, will be able to supply the domestic hot water as well.
I advise you, the homeowner, to hire an architect knowledgeable in the implementation of straw as a building material. Also, the architect should be knowledgeable in sustainable design and renewable energy systems. Properly detailed construction documents outlining construction details, performance standards and implementation of the renewable energy systems will minimize changes and on-site engineering during construction, reducing the construction costs and, ultimately, the home's energy and life cycle costs.