ACH - Air changes per hour. Outside air that building is constantly infiltrating through cracks in a building shell and exchanging with inside air. ACH is the measure of the rate at which this occurs. For example, an ACH or 0.5 means that all the air in the building will change out in two hours.
AFUE - Annual Fuel Utilization Efficiency. Ratio used to rate furnace and boiler efficiencies by dividing the ratio of heat/energy output by heat input. This measurement describes how well fuel; gas or oil is consumed to produce heat by a furnace. As the AFUE rate increases, the furnace efficiency increases, lowering fuel costs. US manufactured furnaces are required to have at 80%+ rating.
Air Handler - The indoor component that moves the heated or cool air throughout duct work. An air handler is usually a blower coil or a furnace.
ASHRAE - American Society of Heating, Refrigeration and Air Conditioning Engineers
Building Automation System (BAS) – Intelligent network of electronic devices, designed to monitor and control the mechanical and lighting systems in a building. Maintains range of building climate, provides lighting based on an occupancy, and monitors system performance and device failures to notify building engineering staff. The BAS functionality reduces building energy and maintenance costs vs. a non-controlled building.
Building Envelope - Exterior surface or shell of a building's construction, e.g. walls, windows, floors, roof, and floor.
Central Duct System - Duct distributes air throughout the air conditioned space and grillwork allows for the return air delivery, which is directed back to the air handling system. When correctly installed, temperature balanced throughout the space for maximum comfort.
Charrette - An intensive and collaborative design process which involves all project stakeholders at the beginning of a building project to develop a comprehensive plan or design. Establishes groundwork for communication and a team-oriented approach to be carried throughout the building process.
Chiller - A device that generates a cold liquid that is circulated through an air-handling unit's cooling coil to cool the air supplied to the building.
Cooling Load - The hourly amount of heat that must be removed from a building to maintain indoor comfort (measured in British thermal units [Btu]).
Cooling Tower - Device which dissipates the heat from water-cooled systems by spraying the water through streams of rapidly moving air. Cooling towers can be substantial water users, and provide an opportunity for water conservation.
Daylighting - The use of controlled natural lighting methods indoors through skylights, windows, and reflected light.By utilizing solar light, daylighting creates a stimulating and productive environment for building occupants.
Degree-Day - The difference between the average daily temperature and 65 degrees Fahrenheit, used as a baseline to estimate building energy needs and compare climate conditions. Also calculated to estimate cooling requirements.
DOE - The Department of Energy is a federal agency responsible for establishing industry efficiency standards and monitoring the consumption of energy sources.
EPA - The Environmental Protection Agency. The EPA develops and enforces federal environmental regulations as well as oversees the Energy Star Program.
Energy Audit - To accurately determining the current energy consumption for a given building area.
Energy recovery ventilator (ERV) - Air to air heat exchanger or preconditioner, designed to reduce the energy required to heat or cool required outdoor air in mechanical ventilation systems by as much as 80%. These products exchange temperature and moisture properties from one airstream to another. The result is capturing the cooling or heating energy from the exhaust air before it leaves the building.
ENERGY STAR - US Environmental Protection Agency (EPA) program introduced in 1992 as a voluntary labeling program designed to identify and promote energy efficient products to help reduce greenhouse gas. The ENERGY STAR blue and white label covers a range of high efficiency products, including computers, lighting, major appliances, and expanded programs include homes, as well as commercial and industrial buildings. For example, homes built to a high standard of energy efficiency (at least 15% more efficient than the International Energy Conservation Code) qualify as Energy Star Homes.
Geothermal Ground Source Heat Pump - These heat pumps are underground coils to transfer heat from the ground to the inside of a building.This type of heat pump can realize substantial energy savings over conventional heat pumps, by using the naturally more stable temperature of the earth as its heat source.
Green Roof - A roof partially or fully covered by vegetation. By creating roofs with a vegetated layer, the roof can counter-act the heat island effect as well as provide additional insulation.
Heat Island Effect - Occurs when warmer temperatures are experienced in urban landscapes compared to adjacent rural areas as a result of solar energy retention on constructed surfaces. Can be up to 10 degrees F difference. Surfaces that contribute include streets, building roofs and parking lots.
Heat Pump - An electric device with both heating and cooling capabilities. It extracts heat from one medium at a lower (the heat source) temperature and transfers it to another at a higher temperature (the heat sink), thereby cooling the first and warming the second.
Heat Recovery Unit/Ventilator - Air-to-air heat exchangers with balanced exhaust and supply fans that meet all necessary ventilation needs without producing drafts or air pressure imbalance on a heating or cooling system. Exhaust fans warm the incoming air with the heat from the outgoing air, recovering about 50-70% of the energy. In hot climates the function is reversed so that the cooler inside air passes by the incoming hot air and reduces its temperature.
HSPF – Heating Seasonal Performance Factor. Rates the efficient operation of the heating portion of the heat pump. As the HSPF increases, the unit functions at a more efficient level. New units in the United States have HSPF ratings from 7.0 to 9.4.
HVAC/R - Heating, Ventilation, Air Conditioning and Refrigeration. Describes the entire indoor air quality and environmental comfort. HVAC incorporates the entire system, from the actual heating and air conditioning units to the duct system supplying the air throughout the structure.
High Efficiency - General term for technologies and processes that require less energy, water, or other inputs to operate. A goal in sustainable building is to achieve high efficiency in resource use when compared to conventional practice. Setting specific targets in efficiency for systems (e.g., using only EPA Energy Star certified equipment, furnaces with an AFUE rating above 90%, etc.) and designs (e.g., watts per square foot targets for lighting) help put this general goal of efficiency into practice.
Hydronics – Describes use of water as the heat-transfer medium in heating and cooling systems. In large-scale commercial buildings such as high-rise and campus facilities, a hydronics system may include both a chilled and a heated water loop. Chillers and cooling towers are used separately or together as means to provide water cooling, while boilers heat water.
Indoor Air Quality (IAQ) - ASHRAE defines acceptable indoor air quality as air in which there are no known contaminants at harmful concentrations and with which 80% or more people exposed do not express dissatisfaction. The nature of air inside the space that affects the health and well-being of building occupants.
Integrated design - Holistic process that considers the many disparate parts of a building project, and examines the interaction between design, construction, and operations, to optimize the energy and environmental performance of the project. The goal of integrated design is to heal damaged environments and become net producers of energy, healthy food, clean water and air, and healthy human and biological communities.
KWH - Kilowatt hours is an electrical term. 1 KwH equals the use of 1000 watts for one hour.
LED - Light Emitting Diode. An electronic light source that is highly energy efficient and environmentally sound. Recent improvements have further reduced size and energy consumption while improving the rendering of color, allowing for more applications. Heat load will be greatly reduced and is key to energy savings.
LEED™ - A self-assessing green building rating system developed by the U.S. Green Building Council. LEED™ stands for Leadership in Energy and Environmental Design, and evaluates a building from a systems perspective. By achieving points in different areas of environmental performance, a building achieves a level of "certification" under the system.
Load Calculations - Heating and cooling loads can be determined using a whole house approach or performing a room-by-room load calculation. The room-by-room approach provides the information needed to determine the number of cubic feet per minute (cfm) needed of conditioned air to satisfy the heating and cooling load for the room.
NEEB - National Environmental Balancing Bureau (NEBB). International association certifying firms and qualifying supervisors and technicians in the following disciplines: Testing, Adjusting, and Balancing (TAB) of HVAC systems; Building Systems Commissioning (BSC); Sound and Vibration Measurement (S&V); Retro-commissioning (RCX); Fumehood Testing (FHT); and Cleanroom Performance Testing (CPT). NEBB also establishes and maintains industry standards, procedures, and work specifications for these disciplines.
Passive Solar - Strategies for using the sun’s energy to heat (or cool) a space, mass, or liquid. Passive solar strategies use no pumps or controls to function. A window, oriented for solar gain and coupled with thermal mass is an example of a passive solar technique.
Photovoltaics (PVs) - Solid-state cells (typically made from silicon) that directly convert sunlight into electricity.
Preventative Maintenance - Maximize the lifecycle of your heating or cooling unit and guard against many unexpected failures. Preventative maintenance inspections performed on a regular basis can uncover leaks, rust, rot, soot, frayed wires and corroded electrical contacts. Inspections on boiler and furnace systems should include ductwork, pipes, dampers, valves, the chimney, registers, radiators, pumps, blowers, fuel lines, the gas meter, oil tank and every part of the actual furnace and boiler. Meanwhile, heat pump and air conditioning unit inspections should also include inspections of the fan, compressor, indoor coils, outdoor coils and refrigerant lines. Annual Service Agreements provide greater efficiency throughout your system.
R-410A (aka Puron) – Environmentally friendly chlorine-free refrigerant that meets the EPA’s most up to date, stringent environmental guidelines. Considered to be the most likely replacement for R-22.
Radiant Heat - Heat transferred in the form of light energy (including non-visible spectra). Distinct from conductive heat, occurring with the direct contact between two materials.
Refrigerant – Refrigerant, or Freon, interacts chemically inside the entire system. The most common refrigerant is currently R-22; however, beginning in 2010, EPA guidelines have established a reduction in R-22 production to a complete cessation in 2020. The “new” Freon is R-410a, which is more environmentally friendly.
R-value - A unit of thermal resistance used for comparing insulating values of different materials; the higher the R-value, the greater its insulating properties.
SEER - The Seasonal Energy Efficiency Ratio defines the energy efficiency of an air conditioner. . The more efficient the unit (the higher the SEER), the less electricity/gas/fuel your HVAC system will use and the lower your energy bill. Effective January 26, 2006, national law requires all HVAC systems manufactured to be a minimum of 13 SEER. Note: EER - Energy Efficiency Ratio is the cooling capacity in BTU/hr divided by electrical energy consumed in watts.
Solar collector - Device which uses the sun’s energy to perform some kind of mechanical advantage which would normally be supplied by a non-renewable energy source. Photovoltaic panels (PV’s) which convert the sun’s energy directly into electricity, and solar hot water panels, which heat pre-heat water before sending it into a hot water heater are two examples.
Stack Effect - Air, as in a chimney, that moves upward because it is warmer than the ambient atmosphere.
Sustainability - Meeting the needs of the present without compromising the ability of future generations to meet their own needs.
Thermal Mass - A mass (often stone, concrete, or brick) used to store heat and reduce temperature fluctuation in a space, by releasing heat slowly over time.
Ventilation Rate - The rate at which indoor air enters and leaves a building. Expressed as the number of changes of outdoor air per unit of time: air changes per hour (ACH), or the rate at which a volume of outdoor air enters in cubic feet per minute (CFM).
Water-Source Heat Pump - Heat pump that uses wells or heat exchangers to transfer heat from water to the inside of a building. Most such units use ground water.
VFD – Variable Frequency Drive. System for controlling the rotational speed of an AC electric motor by controlling the frequency of the electrical power supplied to the motor.
Zoning - Method of dividing a home or office into independently controlled comfort areas for enhanced comfort and efficiency. Larger spaces tend to have zones to differentiate the various areas being air-conditioned.