June 22, 2010
House Call Program: Terminology and Definitions
Benchmark – comparing building’s energy consumption adjusted for building area and climate with energy consumption of other buildings in the same category.
British Thermal Unit (BTU) – is a unit of energy used to describe heating and cooling systems. One BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.
Building envelope – the elements of a building that separate conditioned spaces from the exterior.
Chimney/Stack Effect – is the movement of air into and out of buildings. It driven by the difference in indoor-to-outdoor temperature and moisture. Stack effect pushes hot air out of the buildings on the top floors and sucks cold air into the buildings on the lower flowers during winter. The sequence is reversed in summer.
Cooling Degree Day (CDD) -it is a difference between a mean temperature for the day (if it is more than 65F) and the base, 65F. Annual cooling degree days is a sum of the degree days of the calendar year.
Energy audit – an analysis of energy flows in a building aimed at finding ways to reduce energy consumption and improve human comfort, health and safety.
Energy reduction plan – report outlining energy saving measures for a particular building.
Energy Star – is a Program for energy efficient products. Devices carrying the Energy Star logo, such as computer, appliances, buildings products must perform better than the minimum standards by a certain margin. For example, 2008 models of refrigerators need to be 20% and dishwashers – at least 41% better than minimum standards to be labeled as Energy Star.
Energy Star Performance Rating – a rating systems for commercial and institutional building types and manufacturing facilities. These ratings, on a scale of 1 to 100, provide a means for benchmarking the energy efficiency of specific buildings a against the energy performance of similar facilities. The rating systems are also used by EPA to determine if a building or plant can qualify to earn ENERGY STAR recognition.
Heating Degree Day (HDD) – it is a difference between a mean temperature for the day (if it is less than 65F) and the base, 65F. Annual heating degree days is a sum of the degree days of the calendar year.
NESEA – Northeast Sustainable Energy Association. Promotes the understanding, development, and adoption of energy conservation and non-polluting, renewable energy technologies.
NYSERDA – New York State Energy Research and Development Authority. Strives to facilitate change through the widespread development and use of innovative technologies to improve the State’s energy, economic, and environmental wellbeing.
Payback Time – period of time required to recoup the initial investment.
Return on Investment (ROI) – a performance measure used to evaluate the efficiency of an investment and calculated as the benefit (return) of an investment is divided by the cost of the investment.
Savings Investment Ratio (SIR) – ratio of savings to costs calculated by dividing the future savings by the initial investments. If SIR is above 1, the measure will pay for itself during its lifetime.
Thermostatic Radiator Valve (TRV) – is a self regulating valve fitted to radiators. TRVs work by allowing steam or hot water into the radiator until the room reaches the temperature set on the control dial. They then close and do not allow more steam into the radiator. When the room temperature falls below the setpoint, the valve reopens, allowing steam or hot water to enter the radiator again. TRVs can be easily adjusted to keep a room at a desired setpoint, which gives individual occupants the most control.
Useful Life – the number of years that depreciable equipment or property is expected to be in use.