Building Performance
Buildings are a system made up of many different components that work together, some mechanical, think of a furnace, air conditioner, or heat pump, and some are part of the building itself, such as drywall, insulation, and foundation. Each of these parts have a role to play in either helping the other components function efficiently and as intended, or if improperly installed, sized, or acting to fix a symptom of a more fundamental issue, causing the people inside to be uncomfortable or using more energy than should be necessary. This can happen if a thorough analysis of the entire building as a system is not performed when upgrading or replacing HVAC equipment, renovations, or a whole host of other building upgrades. The specialists that perform these analyses train in the field of Building Science. Building Science helps us see the building as a whole instead of discrete sections that operate independently of one another.
The building shell is typically divided into two components.
Air Barrier (& Vapor Retarder if separate from Air Barrier)
The air barrier is the component of the building shell that keeps air from exchanging between the outside and inside. Often this is a plastic sheet inside the wall, the drywall, a combination of a plastic sheet and drywall, or lath and plaster (depending on the age of the building). The “tightness” of a building is used to describing how well air sealed the building is. This can be determined by a blower door test to give the “tightness” a value to benchmark and improve upon.
Thermal Barrier
The thermal barrier is the component which is often thought of as insulation in the home, which is true, but all components of the home have varying degrees of R-value, or how well something insulates. The higher the R-value, the better thermal barrier a specific material is. The insulation material, depth, and quality of installation, impacts the effectiveness of the insulation. The effective R-value of the insulation can be approximated using a thermal imaging camera.
These two are most effective when working together, and in some instances, the thermal barrier will function significantly worse without a proper air barrier.
Do you ever wonder why the air in your home or office is wet in the summer and dry in the winter?
These swings in moisture can also be attributed to the building shell. When their are gaps in the air barrier of your building, this leads to air easily moving in and our of your home or office. Air carries moisture in it and the amount of moisture depends on the temperature of the air. Warm air can hold more moisture than cold air which for a home that leaks air, means that in the summer your building will be more humid and in the winter, will be more dry. If the moisture stayed in the air, this wouldn’t be an issue, but it condenses (turns from water vapor to liquid water) on cool surfaces, just like the perspiration on a cold glass during the summer time. This is a problem in homes in the winter because moisture from the air travels through cracks and condenses on the first cold surface it touches, which could be insulation in your attic or beneath your roof. Over time this will cause wood to rot and mold to form, resulting in structural issues or indoor air quality issues, such as more frequent colds, sinus issues, allergies, etc.