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Heating Degree Day
Heating degree day (HDD) is a measurement designed to quantify the demand for energy needed to heat a building. HDD is derived from measurements of outside air temperature. The heating requirements for a given Architectural structure, building at a specific location are considered to be directly proportional to the number of HDD at that location. Related measurements include the cooling degree day (CDD), which quantifies demand for air conditioning. Definition Heating degree days are defined relative to a base temperature—the outside temperature above which a building needs no heating. Base temperatures may be defined for a particular building as a function of the temperature that the building is heated to, or it may be defined for a country or region for example. In the latter case, building standards or conventions may exist for the temperature threshold. These include: The base temperature does not necessarily correspond to the building mean internal temperature, as standa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Heating Degree Day Map, 1961-1990
United may refer to: Places * United, Pennsylvania, an unincorporated community * United, West Virginia, an unincorporated community Arts and entertainment Films * ''United'' (2003 film), a Norwegian film * ''United'' (2011 film), a BBC Two film Literature * ''United!'' (novel), a 1973 children's novel by Michael Hardcastle Music * United (band), Japanese thrash metal band formed in 1981 Albums * ''United'' (Commodores album), 1986 * ''United'' (Dream Evil album), 2006 * ''United'' (Marvin Gaye and Tammi Terrell album), 1967 * ''United'' (Marian Gold album), 1996 * ''United'' (Phoenix album), 2000 * ''United'' (Woody Shaw album), 1981 Songs * "United" (Judas Priest song), 1980 * "United" (Prince Ital Joe and Marky Mark song), 1994 * "United" (Robbie Williams song), 2000 * "United", a song by Danish duo Nik & Jay featuring Lisa Rowe Television * ''United'' (TV series), a 1990 BBC Two documentary series * ''United!'', a soap opera that aired on BBC One from 1965-19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Building Insulation
Building insulation is any object in a building used as insulation for thermal management. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation (e.g. for vibrations caused by industrial applications). Often an insulation material will be chosen for its ability to perform several of these functions at once. Insulation is an important economic and environmental investment for buildings. By installing insulation, buildings use less energy for heating and cooling and occupants experience less thermal variability. Retrofitting buildings with further insulation is an important climate change mitigation tactic, especially in geographies where energy production is carbon-intensive. Local and national governments and utilities often have a mix of incentives and regulations to encourage insulation efforts on new and renovated buildings as part of efficiency programs in order to red ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sol-air Temperature
Sol-air temperature (''T''sol-air) is a variable used to calculate cooling load of a building and determine the total heat gain through exterior surfaces. It is an improvement over: :\frac = h_o(T_o - T_s) Where: * q = rate of heat transfer * A = heat transfer surface area 2* h_o = heat transfer coefficient for radiation (long wave) and convection /m2K* T_o = outdoor surroundings' temperature °C* T_s = outside surface temperature °C The above equation only takes into account the temperature differences and ignores two important parameters, being 1) solar radiative flux; and 2) infrared exchanges from the sky. The concept of ''T''sol-air was thus introduced to enable these parameters to be included within an improved calculation. The following formula results: T_\mathrm = T_o + \frac Where: * a = solar radiation absorptivity (surface solar absorptance or the inverse of the solar reflectance of a material) * I = global solar irradiance (i.e. total solar radiation incident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heating, Ventilation, And Air Conditioning
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers). HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh ai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Degree Day
A degree day is a measure of heating or cooling. Total degree days from an appropriate starting date are used to plan the planting of crops and management of pests and pest control timing. Weekly or monthly degree-day figures may also be used within an energy monitoring and targeting scheme to monitor the heating and cooling costs of climate controlled buildings, while annual figures can be used for estimating future costs. A degree day is computed as the integral of a function of time that generally varies with temperature. The function is truncated to upper and lower limits that vary by organism, or to limits that are appropriate for climate control. The function can be estimated or measured by one of the following methods, in each case by reference to a chosen base temperature: * Frequent measurements and continuously integrating the temperature deficit or excess; * Treating each day's temperature profile as a sine wave with amplitude equal to the day's temperature variation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relative Humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depends on the temperature and pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is the dew point. The amount of water vapor needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 g of water per cubic metre of air at , but only 8 g of water per cubic metre of air at . Three primary measurements of humidity are widely employed: absolute, relative, and specific. Ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hours, to global winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The two main causes of large-scale atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet (Coriolis effect). Within the tropics and subtropics, thermal low circulations over terrain and high plateaus can drive monsoon circulations. In coastal areas the sea breeze/land breeze cycle can define local winds; in areas that have variable terrain, mountain and valley breezes can prevail. Winds are commonly classified by their spatial scale, their speed and direction, the forces that cause them, the regions in which they occur, and their effect. Winds have various asp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Appliance
A home appliance, also referred to as a domestic appliance, an electric appliance or a household appliance, is a machine which assists in household functions such as cooking, cleaning and food preservation. Appliances are divided into three types: small appliances, major appliances (also known as white goods) and consumer electronics (brown goods). Definition Given a broad usage, the domestic application attached to home appliance is tied to the definition of appliance as "an instrument or device designed for a particular use or function". More specifically, Collins English Dictionary defines "home appliance" as: "devices or machines, usually electrical, that are in your home and which you use to do jobs such as cleaning or cooking". The broad usage, afforded to the definition allows for nearly any device intended for domestic use to be a home appliance, including consumer electronics as well as stoves, refrigerators, toasters and air conditioners. History While many appl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Radiation
Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m2) in SI units. Solar irradiance is often integrated over a given time period in order to report the radiant energy emitted into the surrounding environment (joule per square metre, J/m2) during that time period. This integrated solar irradiance is called solar irradiation, solar exposure, solar insolation, or insolation. Irradiance may be measured in space or at the Earth's surface after atmospheric absorption and scattering. Irradiance in space is a function of distance from the Sun, the solar cycle, and cross-cycle changes.Michael Boxwell, ''Solar Electricity Handbook: A Simple, Practical Guide to Solar Energy'' (2012), p. 41–42. Irradiance on the Earth's surface additionally depends on the tilt of the measuring surface, the height ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balance Point Temperature
The building balance point temperature is the outdoor air temperature when the heat gains of the building are equal to the heat losses. Internal heat sources due to electric lighting, mechanical equipment, body heat, and solar radiation may offset the need for additional heating although the outdoor temperature may be below the thermostat set-point temperature. The building balance point temperature is the base temperature necessary to calculate heating degree day to anticipate the annual energy demand to heat a building. The balance point temperature is a consequence of building design and function rather than outdoor weather conditions. Mathematical definition The balance point temperature is mathematically defined as: Equation 1: ' Where: *''tbalance'' is the balance point outdoor air temperature, given in °C (°F). *''tThermostat'' is the building thermostat set-point temperature, given in °C (°F). *''QIHG ''is the internal heat generation rate per unit floor area due to oc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
U-value
In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. R-value is the temperature difference per unit of heat flux needed to sustain one unit of heat flux between the warmer surface and colder surface of a barrier under steady-state conditions. The ''R-value'' is the building industry term for thermal resistance "per unit area." It is sometimes denoted RSI-value if the SI units are used. An R-value can be given for a material (e.g. for polyethylene foam), or for an assembly of materials (e.g. a wall or a window). In the case of materials, it is often expressed in terms of R-value per metre. R-values are additive for layers of materials, and the higher the R-value the better the performance. The U-factor or U-value is the overall heat transfer coefficient and can be found by taking the inverse of the R-value. It is a property t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermal Mass
In building design, thermal mass is a property of the mass of a building that enables it to store heat and provide inertia against temperature fluctuations. It is sometimes known as the thermal flywheel effect. The thermal mass of heavy structural elements can be designed to work alongside a construction's lighter thermal resistance components to create energy efficient buildings. For example, when outside temperatures are fluctuating throughout the day, a large thermal mass within the insulated portion of a house can serve to "flatten out" the daily temperature fluctuations, since the thermal mass will absorb thermal energy when the surroundings are higher in temperature than the mass, and give thermal energy back when the surroundings are cooler, without reaching thermal equilibrium. This is distinct from a material's insulative value, which reduces a building's thermal conductivity, allowing it to be heated or cooled relatively separately from the outside, or even just retain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
