For that state of “thermal comfort”Temperatures around 20°C in winter and 25°C in summer, along with humidity levels between 40% and 70%, are generally considered normal. To maintain these conditions consistently, it is important to keep in mind that the temperature of a room is affected by a multitude of factors, including: the angle of sunlight, the size and placement of windows, the material of the walls, the outside temperature, and many others.
The thermal load
This gives rise to the need to use a method that allows us to accurately determine the HVAC requirements of a space—regardless of its purpose—so that it can reach the desired temperature. We are talking about the thermal load of a given space, and applies to everything from a home—where a heating system is to be installed—to an industrial refrigerator.
The heat load of a given space is calculated in kilocalories per hour (kcal/h) and must be determined before designing the HVAC systems for any room, facility, or building. In fact, it is calculated based on “design scenarios” which are typically the most extreme conditions of each season—that is, the coldest day of winter and the hottest day of summer—since it takes less energy to cool a space than to heat it.
Factors Affecting a Building's Heat Load
We've already touched on some of the factors that make fluctuations in temperature and humidity inside a building, that is, they have a significant impact on the calculation of the heat load. These factors can themselves be considered heat loads, and they are divided into two groups.
- Factors from the external environment: These are factors that originate outside the space or building in question. They are:
- Loads transmitted through building envelopes: These are the loads that are transmitted through the opaque building envelopes of a space, such as walls, roofs, and floor slabs.
- Heat transfer through glazed surfaces: This refers to heat transfer through windows or skylights, which is much greater than that through opaque enclosures.
- Heat loads introduced through the ventilation system: These result from the heat in the air entering as part of the ventilation system, given that this air is periodically replaced.
- Loads due to air infiltration: These are similar to loads introduced through ventilation, but with the difference that they are not part of the ventilation system.
- Factors related to the indoor environment: These are factors that originate within the space or building itself.
- Heat generated by people: This refers to the heat produced by the people occupying the space, which is mainly transmitted through breathing.
- Lighting loads: This refers primarily to the heat generated by light bulbs and shades during the process of producing artificial light.
- Heat generated by electrical and/or computer equipment: Almost all computer equipment generates heat due to its electronic components, and when several pieces of such equipment are grouped together, they release a considerable amount of heat into the surrounding environment.
- Other internal heat loads: There may always be heat loads resulting from specific activities carried out within the spaces, such as heavy machinery or the handling of materials at high temperatures.
Although we can say that calculating the thermal loads required for building HVAC is not extremely complex, and the method for doing so is outlined in the building codes of most countries; It is very important to know how to interpret the influence of each factor, which can only be achieved by a professional with expertise in the field and the necessary tools to carry them out.
Professionals who are increasingly in demand in the construction and architecture sectors due to the growing complexity of HVAC systems and energy efficiency. And who have come to specialize in this aspect of construction
