Airtight Construction
With airtight construction, there are no unintended gaps in the building envelope that allow air to leak in or out of the building or cold drafts to come in through the building envelope.

Blower Door Test 
A powerful fan that mounts into the frame of an exterior door. The fan pulls air out of the house, lowering the air pressure inside. The higher outside air pressure then flows in through all unsealed cracks and openings. These tests determine the air infiltration rate of a building.

Cubic feet per minute.

Deep Energy Retrofits
A whole-building analysis and construction process that uses “integrative design” to achieve much larger energy savings than conventional energy retrofits.

Dense Pack Cellulose
Cellulose insulation is made from recycled newspaper and reconstituted wood pulp. The material is treated with Borate, a naturally occurring mineral compound which greatly increases fire, moisture, mold, and vermin resistance. It stops air infiltration and offers excellent sound insulation. When cellulose is pneumatically installed at high velocity to densities greater than 3.5 pounds per square foot, it acquires a unique air sealing property. In this process, the material behaves as a liquid, flowing into obscure bypasses and solidifying them.

Energy Star
An international standard for energy-efficient consumer products that generally use 20–30% less energy than required by federal standards.

Energy recovery ventilation.

Global warming potential.

Heat Pump Hot Water Heater 
Using electricity to run a compressor, a heat-pump water heater (HPWH) extracts heat from air, often in the basement, and transfers that energy to heat water in a tank. It’s like a refrigerator, only running backward: A refrigerator moves heat from its interior to the room it’s located in. An HPWH transfers heat from the room to a storage tank, and does it with remarkable efficiency. In fact, an HPWH is able to transfer more energy (up to 2.5 times) than the electricity it consumes.

Hight-Performance Tilt Turn Windows
The premise of the design is to provide a window that offers draft-free ventilation, easy cleaning, and egress. Draft-free ventilation is achieved when a user tilts the window allowing hot stagnant air at the ceiling to escape and cooler fresh air to enter the room around the sash.

Heat recovery ventilation.

Indoor Air Quality-low particulate matter %, VOC ppm, CO2 ppm.

Life Cycle Assessment
A technique to assess environmental impacts associated with all the stages of a product’s life from raw material extraction through materials processing, manufacture, distribution, use, repair, and maintenance.

Mineral Wool/Rock Wool
An insulation product made from actual stone that is very heat resistant; a good insulator and sound retardant.

Mini Splits 
Highly-efficient ductless heating and cooling system.

Net Zero
A building with zero net energy consumption, meaning the total amount of energy used by the building on an annual basis is roughly equal to the amount of renewable energy created on the site.

Passivhaus (passive house)
A rigorous, voluntary standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling.

Photovoltaics (PV) 
A typical photovoltaic system employs solar panels, each comprising a number of solar cells, which generate electrical power, through the conversion of light into electricity using semiconducting materials.

“R” Value
The capacity of an insulating material to resist heat flow. The higher the R-value, the greater the insulating power.

Solar Heat Gain Coefficient (SHGC)
The fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.

Solar Thermal
A technology that uses the sun’s energy, rather than fossil fuels, to generate low-cost, environmentally friendly thermal energy. This energy is used to heat water or other fluids, and can also power solar cooling systems.

An approach to building design, construction, and retrofitting that dramatically reduces heat loss (and gain) by using much higher levels of insulation and air tightness than normal.

U-values measure how effective a material is as an insulator. The lower the U-value, the better the material as a heat insulator.

Volatile organic compound.