Building Science and Building Enclosures Research Thrust
Most problems in residential buildings relate to serviceability and are caused by moisture or rain penetration from the exterior and condensation within and on walls or glazing surfaces, which could lead to mold growth. These moisture/vapor related issues, air leakage and thermal comfort issues, as well as energy efficiency aspects constitute technical areas that require an understanding of the principles of building science to overcome, resolve, and prevent the associated problems.
Products such as windows, air and vapor barriers, and thermal insulation are required to be tested for air and/or water leakage resistance, or performance. Normally, the air and vapor barrier membrane is tested by the manufacturer. However, the whole house air leakage performance is an important aspect for energy performance, evaluated using what is known as a blower door test. To ensure acceptable product performance, windows need to be tested in place for air infiltration, water penetration, and thermal performance, and their glazing needs to be tested for the solar heat gain coefficient, shading coefficient, U-factor, and visible transmissibility, among other energy or durability performance criteria.
Another research area of great importance in relation to humidity and ventilation is indoor air quality, which can affect the health of the occupants. In general, excessive humidity in homes, in the form of air moisture content, measured as relative humidity, brings about the conditions for mold growth and allergens, such as dust mites and pests that cause allergies or asthma. The two primary causes of poor indoor air quality leading to illnesses are more air-tight homes designed to conserve energy but without proper ventilation systems, and the use of synthetic building materials, furnishings, and finishes. Air-tight homes do not get much fresh air, and the trapped air will have increased pollutant concentration. Higher humidity in homes due to leaks and uncontrolled sources of moisture can also lead to an increased concentration of allergens and more excessive mold growth. Unwanted moisture in homes can be controlled in various ways, including fixing leakage/seepage, using exhaust fans and dehumidifiers, and raising the temperature of cold surfaces where moisture could condense. Mold can grow if mold spores land on a wet surface and stay there long enough at the right temperature. Molds produce allergens, irritants, and in some cases, toxic substances. All such issues can be avoided or minimized by using proper design and detailing for the walls and windows. Normally, construction of mockups and lab testing can help validate proper design and detailing.
