William Maclay - Vermont Architects and Planners
Choices in Sustainability

Air infiltration: The rate of air leakage through the insulated exterior surfaces of a building, measured in CFM50 per square foot of surface area.

Air source heat pump (ASHP):
A high-efficiency electric heating and cooling system which can be powered by on-site generated electricity.

Taking inspiration from nature or emulating its patterns to solve human problems.

The hypothesis that there is an innate connection between human beings and all other living systems.

Blower door test:
A test to measure the rate of air leakage in a building. This is often done to ensure the effectiveness of air sealing measures.

Carbon footprint:
A measure of environmental impact expressed in tons of carbon dioxide emissions.

Carbon dioxide (CO2):
A greenhouse effect causing gas resulting from the burning of fossil fuels.

Carbon neutral:
The state of zero net carbon emissions. In the case of a building, it generates as much clean energy as it consumes.

Coefficient of performance (COP):
A measure of efficiency of an electric heating system compared to a baseline of electric resistance heat.

The process of evaluation and modification of building systems through the design process and post occupancy to ensure the targeted goals of efficiency and comfort are achieved.

Cradle to cradle:
A perpetual system in which materials can be continually repurposed, recycled or composted without downgrading or becoming waste. A product can be C2C certified as a cradle to cradle product.

Ecological footprint:
A measure of the land and water required to support a product, building or practice. This measure is used to determine how ‘environmentally friendly’ it is.
Embodied energy: A measure of the total amount of energy expended in the creation of a product.

Energy Recovery Ventilation (ERV):
A device which recovers both the heat and humidity of exhausted air and uses it to preheat incoming air.

The exterior insulated shell of a building, including walls, roof, foundation, windows and doors.

Ground source heat pump (GSHP):
A heating and cooling system which uses wells to extract heat from the ground for heating or disperses heat into the ground for cooling.

Heat island effect:
Increased temperature resultant from a high concentration of pavement, buildings and other heat-retaining surfaces.

Heat Recovery Ventilation (HRV):
A device which recovers the heat of exhausted air and uses it to preheat incoming air.

Indoor air quality (IAQ):
A measure of the quality of indoor air achieved through the use of low noxious gas emitting materials, proper moisture control and adequate fresh air exchange.

LEED (Leadership in Energy and Environmental Design):
The US Green Building Council’s (USGBC) rating system, which measures the environmental impact and energy performance of a building. Buildings can achieve ratings ranging from Certified to Silver, Gold and Platinum.

Life cycle cost:
The total cost of a material or system over its entire cycle of use which takes into consideration production, extraction, disposal, performance and usable lifespan.

Low emissivity (low-e) glass:
Glass which utilizes a clear film to transmit visible light while filtering heat energy. Depending on application it can reduce heat loss or prevent excessive heat gain from sunlight.

The climatic conditions at the scale of a site or building.

Micro load:
A building with minimized energy consumption through the use of efficient mechanical systems, non-mechanical energy saving strategies and high insulation values.

Net Metering:
A system in which on site renewable power can be sold to the grid for credit during times of excess production, and grid supplied power can be purchased during times of lower on-site production. If annual consumption and production averages are equal, a building can have no net demand, without the instability of traditional ‘off the grid’ renewable systems.

A building which produces as much energy as it consumes on an annual basis.

Net-zero ready:
A highly efficient building with minimal energy loads that with the future addition of renewables can become net-zero.

The emission of noxious gasses from materials which can result in poor air quality and can cause sickness. The condition is greatest at installation and dissipates over time.

Passive solar:  
The use of natural heat transmission processes to gain heat from the sun without the aid of mechanical systems.

Passive strategies:
Energy reducing measures which do not utilize mechanical equipment such as orientation towards the sun for heat gain or utilizing efficient building forms to maximize the ratio of interior volume to insulated area.

Photovoltaic (PV): 
A panel which converts solar energy into electricity.

Post-consumer recycled content:
The percentage of material in a product recycled from used consumer products.

Post-industrial recycled content:
The percentage of material in a product recycled from completed manufacturing processes.

Post occupancy evaluation:
Evaluation of a buildings performance during its initial occupancy to ensure the systems operate with the intended efficiency and that occupants are comfortable.

The measure of a material or assembly of material’s ability to insulate. The inverse of U-value. High R-values are desirable.

Renewable energy:
Sources of energy which can be perpetually maintained, such as solar and wind power, as opposed to non-renewable energy such as fossil fuels.

Renewable ready:
A highly efficient building with minimal energy loads which is ready for the installation of on-site renewable energy sources.

Return on investment (ROI):
An economic indicator used to assess the effectiveness of an investment, measuring savings over time compared to the initial capital investment. Figures are often used to weigh the upfront costs of energy saving measures against the long term energy savings of reduced fuel consumption.

Sick building syndrome (SBS):
Health issues suffered by building occupants related to the quality of the air. SBS can be mitigated through the use of low noxious gas emitting materials, moisture control and ventilation.

Solar collector:
A panel used to absorb energy generated by the sun, for use in either hot water or electricity production.

A material or system which offers a significantly higher than average level of insulation.

A system which can be continually maintained without depleting non-renewable resources.

Solar domestic hot water (SDHW):
A system which uses the sun to preheat hot water for occupant use.

Solar orientation:
The orientation of a building along the true geographic cardinal directions to maximize exposure to the sun for non-mechanical heating in cold climates, or minimize unwanted heat gain in warm climates.

Thermal bridging:
“Short circuits” in the insulation of a building. While parts of the wall may be highly insulated, these “bridges,” such as metal studs, act as a weak link, transferring cold through the wall.

Thermal mass:
A material with the ability to store heat to alleviate the impact of temperature swings. Excess heat is absorbed during the warm day and released during the night as the outside temperature drops.

True north
: Geographic north which differs from magnetic north depending on a specific areas magnetic declination. True north is necessary to accurately determine a building’s orientation to the sun.

The measure of a material or assembly of material’s or inability to insulate. The inverse of R-value. A low U-value is desirable.

Volatile organic compound (VOC):
Compounds found in materials and finishes which evaporate at ambient temperature and can affect the environment and human health negatively.