A glass-fronted office with air conditioning and a stone-vaulted church on a hot summer’s day could both be reading 21°C on a thermometer. But one would be a pleasant place to be and the other a cold storage room. Your body is not a thermometer and it is not just air temperature that affects how you feel. Your body is a heat engine that constantly generates heat and you need to get that heat to escape from your body to stay comfortable. Four main factors affect this and in air conditioned buildings the fourth, mean radiant temperature, is often the least-known but most interesting factor.
Your body is not just a thermometer – it’s a heat engine that constantly generates heat from within and needs to release that heat to the surrounding air in order to remain comfortable. Four key factors determine how well your body can manage this: air temperature, relative humidity, air movement and the mean radiant temperature.
The least known of these factors is the Mean Radiant Temperature (MRT) or the effective temperature of all the surfaces surrounding any point. In a stone walled church such as this, the walls have been cold all winter, and so are unlikely to be radiating much heat to your body even in 21°C conditions. In contrast a plate-glass window that has been in the sun all day will be radiating a lot of heat to you even in 28°C conditions and with the air-con turned down to 21°C. For Air con Gloucester, see https://acecc.co.uk/.
For cooling systems supplied to Gloucester, there are some critical issues that are often not fully appreciated by those that specify and design cooling systems. If, for example, a cooling system is selected on the basis of an assumed cooling load, then it may satisfy the thermometer in the corner of the room, but fail to deliver a comfortable thermal environment for the people in the space. Factors such as humidity, air movement, and in particular, the mean radiant temperature (MRT) around the occupants, all have a significant effect on the thermal comfort of individuals in a space. As mentioned previously, all six factors that influence thermal comfort need to be considered and if any one of the factors are outside of the comfort zone, then all of the other factors will not be able to make up for it. There is a useful background explanation of how thermal comfort is measured in workplaces.
In terms of air conditioning installations for Gloucester buildings, this is more important than it might at first appear. The cooling capacity of an air conditioning system is usually chosen based on the temperature of the air. However, as noted above, a building’s thermal comfort can be affected by a number of factors including humidity, air flow and radiant heat from surfaces. Thus, a system that is able to cool a space to the desired temperature could still result in a number of uncomfortable people. A system that has been correctly chosen to match the thermal characteristics of a building will be able to take all of these factors into account in order to provide optimal comfort to the building’s occupants.
