Whether you love science or not, anyone planning to build a new home can benefit from an understanding of the science that affects home construction. Everyone wants a home that is affordable, comfortable, healthy and durable. Utilizing the components of proper building science when planning for your new home can allow you to achieve these things.
It may be science, but it simply comes down to keeping the outside from the inside. When that is not done, problem areas arise letting in wind, rain, moisture, radon, bugs and uncomfortable temperatures.
The outside forces on a home include wind, heat, humidity, rain, ground water, and radon. The driving forces include pressure, heat and moisture. Holes in a home allow the pressure to drive the air into the path of least resistance. That means a high-performance home must control air flow, thermal flow and moisture flow. The time to take control of these is during the design and construction of the home.
Controlling Air Flow
The common openings or holes in a home include: access panels, ceiling fixtures, sill plates, vents, door and window openings, chimney or furnace chases, and plumbing and duct connections. Any of these areas that have gaps are allowing air to flow in or out. Inside the home, fans from clothes dryers, exhaust fans, fireplaces and whole-house fans may exchange up to 10,000 cubic feet of air.
Controlling Thermal Flow
Heat flows in and out of a home through conduction, convection and radiation. Conduction is when heat energy is transferred by direct contact. Convection is when heat in a gas or liquid form is transferred by the circulation of currents from one area to another. Radiation is when electromagnetic rays are emitted from the surface of an object due to a higher temperature than its surroundings. To control the surface temperatures, air barriers must be properly planned and installed so they are aligned with insulation. Other issues can arise when insulation is improperly installed. It can drop allowing cavities in the wall. Another problem occurs when materials such as wood come in contact with each other allowing the heat to radiate through. An example of this are the studs in a typical stud wall installation.
Controlling Moisture Flow
Most moisture damage to a home comes from air flow because all air carries moisture. A one square-inch hole in a 4’ x 8’ sheet of gypsum board will allow 30 quarts of water to enter the home over one heating season. Moisture entering a home causes condensation on windows, walls, and insulation. Moist conditions can create mold and dry rot within the home.
Applying the steps of building science can control the air flow, thermal flow and moisture flow. The first step is to have proper insulation. This means there are no gaps, voids or compression and the insulation is aligned with the interior surface. The use of structural insulated panels provides insulation that has no gaps, voids or compression. The encapsulated foam is sandwiched between two sheets of oriented strand board with joints sealed during installation.
Complete air barriers must be planned and installed for dropped ceilings, tub walls and attics.
Proper air-sealing is also part of building science. Caulking or expanding foal should be used to seal plumbing penetrations and electrical boxes.
Tight air ducts can be achieved by sealing boots and seams with mastic. Doors and seams should include gaskets or other sealing.
The use of energy efficient windows will reduce heat transfer and can reflect heat and UV rays. Technology may include multiple panes that insulate better reduce heat flow and condensation.
Installing properly size and efficient HVAC systems are also an important part of building science. These systems will have a lower cost, increased efficiency and have a longer lifetime.
Talk to your home builder about these building science components and how they can best provide the building system and construction methods to get you a home that is affordable, comfortable, healthy and durable.
SOURCE: Department of Energy, Energy Star