The air tightness of a house is one of the most critical elements in its energy performance. Low-energy and low-carbon schemes such as PassivHaus, Super E®, Energy Star in North America and Minergie in France, all require an air leakage test to be done on houses before they are certified. In more and more countries in the EU, air leakage tests will be required for all new homes.
Engineering to resist hurricanes and earthquakes
There are simple and inexpensive ways to take measures to improve the chances of your house being damaged or destroyed in a hurricane or earthquake. The measures are similar for either kind of disaster.
Engineered for strength
The best type of structure to resist high winds or an earthquake is a frame house. Solid, concrete walls are strong – if you want to stop a bullet – but are inflexible and will crumble in the erratic shaking and twisting liable to occur during an earthquake or hurricane. Frame houses tend to bend and twist slightly and keep their structural integrity.
Research on high winds
The best hurricane research centres are in the United States, where hurricanes are relatively common. Researchers put full-sized houses in giant wind tunnels and measure performance. One area of intense research is on roof performance. In high winds, a vortex can form around roof edges creating upward pressure on the roof to lift it. Architectural features like dormers may encourage or discourage vortex formation. Ideal roof lines is one of the areas of intense research.
Research on earthquakes
The best earthquake research is happening in Japan, where giant shaker tables are used to simulate the actions of an earthquake. Full-sized houses can be built on these shaker tables. Research has found that, without question, a frame house – either steel or timber – is the best structure type to prevent earthquake damage.
There are two types of damage that can occur during a hurricane. The roof may be lifted or the walls may collapse, and the building itself must withstand objects being thrown at them at high speeds. For the first type of damage, longer nails and steel nailer plates should be used to connect timber members. Special ties can be installed that tie one floor to the next and the roof to the walls. Doors should open outwards, not in. For the second type of damage, windows are in the biggest danger. Once windows break, the chances of losing the roof increase dramatically. In places like Florida, where hurricanes happen often, impact resistant glass, like that installed in automobiles, is being mandated. This can either be introduced during the manufacturing process, or it may be a fi lm you apply to existing windows.