Space cooling load is the rate at which heat is removed from the conditioned space to maintain a constant space air temperature. Depending on how solar heat gain occurs, its effects can be felt immediately or over a period of time. In estimating a cooling load, heat gain from all heat-producing equipment and appliances must be taken into account because they may contribute to either sensible or latent loads, and sometimes both. Both radiation and convection can interact with conduction at the surfaces of walls and roofs. The difference between the space heat gain and the space cooling load is due to the storage of a portion of radiant heat in the structure.
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Conduction occurs across walls and roofs, since they are exposed to a temperature difference between building interiors and the warmer outdoor environment.
There are three different ways in which heat from the sun can reach interior spaces calcu,ation conduction, convection and radiation. Corrections and adjustments are made if the conditions are different.
Commercial and Industrial Buildings. Heat load calculation is a highly specialized, time-consuming and complex task that can only be carried out by a qualified HVAC professional.
It is also a very important step to achieve optimal building performance, providing the basis to select an air-conditioning system of the proper type and capacity for the application at hand: Then, based on the heat load calculated, the HVAC designer recommends the type of air-conditioning system suitable for the application, and its required capacity.
The estimation is not discussed in this lecture note. Space cooling load is the rate at which heat is removed from the conditioned space to maintain a constant space air temperature. The corresponding space cooling load Qfs is: Do not forget to share it. Modern Trends in Building Engineering: This approach helps property coolingg avoid oversized systems with higher initial and running costs than necessary, gvac also undersized systems that deliver insufficient cooling.
Finally, radiation is a direct form of heat transfer that occurs when sunlight enters buildings through windows or other transparent surfaces. Infiltration load is a space cooling load due to the infiltrated air flowing through cracks and openings and entering into a conditioned room under a pressure difference across the building envelope.
In the morning, east-facing walls and windows are exposed to direct sunshine. CLF is used to determine solar loads or internal loads. North Latitude and All Room Construction. As a result, the human contribution to the uvac heat load can be especially high in large air-conditioned spaces like halls, auditoriums, theatres, cinemas and airports. The introduction of outdoor ventilation air must be considered in combination with the infiltrated air.
Heat Load Calculation: Importance in HVAC Design
Use energy-efficient appliances to minimize their heating effect. Calculxtion at rest Seated, very light work, writing Seated, eating Seated, light work, typing, Standing, light work or walking slowly, Light bench work Light machine work Heavy work Moderate dancing Athletics. In estimating a cooling load, heat coloing from all heat-producing equipment and appliances must be taken into account because they may contribute to either sensible or latent loads, and sometimes both.
Electric lights contribute to sensible load only. Correction values for 22 degree north latitude in July are as follows: Overview of the Main Heat Sources Although there are many ways in which heat can be generated, directly or indirectly, the following are some of the main sources in building interiors: Human beings release both sensible heat and latent heat to the conditioned space when they stay in it.
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The heat held by outdoor air comes in great part from the sun, but it can also originate from vehicles or from other buildings. Based on these calculations, the HVAC designer recommends an air-conditioning system of a suitable type and tonnage.
Eqns 3 and 4 are valid to estimate the sensible and latent cooling loads respectively. Therefore, CLF depends on the magnitude of surface and the space air flow rates.
Table 9 aclculation the summer outdoor design dry bulb and wet bulb temperatures at 22 degree north latitude. The exact equations and table values to use are determined based on building geometry, construction materials, and the appliances and building systems found inside.