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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.
Degree days are a useful metric for estimating energy consumption required for household heating and cooling, and in this context are formally referred to as heating degree days. Since the escape or ingress of heat due to conduction is proportional to the difference between the indoor and outdoor temperature, the amount of energy needed to ...
Example of an energy signature showing a linear relationship between daily cooling and heating demand with average daily ambient temperature. In mechanical engineering , energy signatures (also called change-point regression models ) relate energy demand of buildings to climatic variables, typically ambient temperature . [ 1 ]
An example is a diathermic wall that is permeable only to heat; the intensive variable for this case is temperature. When the two bodies have been connected through the specifically permeable wall for a very long time, and have settled to a permanent steady state, the relevant intensive variables are equal in the two bodies; for a diathermal ...
The number is always two or more; usually it is not more than some dozen. Though the number of state variables is fixed by experiment, there remains choice of which of them to use for a particular convenient description; a given thermodynamic system may be alternatively identified by several different choices of the set of state variables.
Firstly, thermo-("of heat"; used in words such as thermometer) can be traced back to the root θέρμη therme, meaning "heat". Secondly, the word dynamics ("science of force [or power]") [22] can be traced back to the root δύναμις dynamis, meaning "power". [23] In 1849, the adjective thermo-dynamic is used by William Thomson. [24] [25]
In chemistry and thermodynamics, calorimetry (from Latin calor 'heat' and Greek μέτρον (metron) 'measure') is the science or act of measuring changes in state variables of a body for the purpose of deriving the heat transfer associated with changes of its state due, for example, to chemical reactions, physical changes, or phase ...
The building balance point temperature is the outdoor air temperature when the heat gains of the building are equal to the heat losses. [1] 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.