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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 estimated average heating energy requirements for a given 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 energy 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 ... [...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), ''United'' (2003 film), a Norwegian film * United (2011 film), ''United'' (2011 film), a BBC Two film * The United (film), ''The United'' (film), an unreleased Arabic-language film Literature * United! (novel), ''United!'' (novel), a 1973 children's novel by Michael Hardcastle Music * United (band), Japanese thrash metal band formed in 1981 Albums * United (Commodores album), ''United'' (Commodores album), 1986 * United (Dream Evil album), ''United'' (Dream Evil album), 2006 * United (Marvin Gaye and Tammi Terrell album), ''United'' (Marvin Gaye and Tammi Terrell album), 1967 * United (Marian Gold album), ''United'' (Marian Gold album), 1996 * United (Phoenix album), ''United'' (Phoenix album), 2000 * United (Woody Shaw album), ''United'' (Woody Shaw album), 1981 Songs * United (Judas Priest song ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
San Diego
San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in the United States. San Diego is the county seat, seat of San Diego County. It is known for its mild Mediterranean climate, extensive List of beaches in San Diego County, beaches and List of parks in San Diego, parks, long association with the United States Navy, and recent emergence as a wireless, electronics, List of hospitals in San Diego, healthcare, and biotechnology development center. Historically home to the Kumeyaay people, San Diego has been referred to as the ''Birthplace of California'', as it was the first site visited and settled by Europeans on what is now the West Coast of the United States. In 1542, Juan Rodríguez Cabrillo claimed the area for Spain, forming the basis for the settlement of Alta California, 200 years later. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Weather Derivative
Weather derivatives are financial instruments that can be used by organizations or individuals as part of a risk management strategy to reduce risk associated with adverse or unexpected weather conditions. Weather derivatives are index-based instruments that usually use observed weather data at a weather station to create an index on which a payout can be based. This index could be total rainfall over a relevant period—which may be of relevance for a hydro-generation business—or the number where the minimum temperature falls below zero which might be relevant for a farmer protecting against frost damage. As is the case with parametric weather insurance, there is no proof of loss provision. Unlike "indemnity" insurance-based cover, there is no need to demonstrate that a loss has been suffered, however an indemnity insurance policy for weather is a rarely utilized instrument. Settlement is objective, based on the final value of the chosen weather index over the chosen period. I ... [...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 o ... [...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 Sick building syndrome, healthy building conditions are regulated with respect to temperature and ... [...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] |
Albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects all incident radiation). ''Surface albedo'' is defined as the ratio of Radiosity (radiometry), radiosity ''J''e to the irradiance ''E''e (flux per unit area) received by a surface. The proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location, and time (see position of the Sun). While directional-hemispherical reflectance factor is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds ... [...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 (meteorology), 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 8 g of water per cubic metre of air at , and 28 g of water per cubic metre of air at Three primary measurements of humidity are widely employed: abso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind
Wind is the natural movement of atmosphere of Earth, air or other gases relative to a planetary surface, 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 (electromagnetic radiation), absorption of solar energy between the climate zones on Earth. The study of wind is called anemology. 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 scale (spatial), spatial ... [...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. 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". ''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 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. The development of self-contained electric and gas-powered appliances, an American innovation, emerged in the early 20th century. This evolution is linked to the decline of full-time domestic servants and desire to reduce household chores, allowing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Radiation
Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible light perceptible to the human eye as well as invisible infrared (typically perceived by humans as warmth) and ultraviolet (which can have physiological effects such as sunburn) lights. However, according to the American Meteorological Society, there are "conflicting conventions as to whether all three ..are referred to as light, or whether that term should only be applied to the visible portion of the spectrum." Upon reaching the Earth, sunlight is scattered and filtered through the Earth's atmosphere as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (atmospheric). When blocked by clouds or reflected off other objects, sunlight is diffused. Sources estimate a global average o ... [...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] |
