Energy management
Thermal comfort When people are in a room, ‘thermal comfort’ comes into play. Researched by P.O. Fanger in the 1970s1
, the concept
relates to the complex relationship between humans and their thermal environment. This consists of factors such as air temperature, air speed, humidity and mean radiant temperature. Although a healthy person is expected
to have a thermometer temperature of 37.4°C, their skin surface temperature is about 31-33°C. If the room temperature is 22°C, then
people lose heat to the room rather than being warmed by it. It is the rate of heat loss that defines whether we are comfortable or not. If the level of heat is too high because
the room is underheated, we feel chilly. However, if heat loss is too low because the room is overheated, it feels stuffy and we feel lethargic. In the care home environment,
thermal comfort can be particularly important as underheating and overheating can result in distress or even violent and challenging behaviour. This is particularly true in people with dementia as well as those with learning disabilities or communication problems. As a result, it is thermal comfort that is
more important to the occupier than thermal output and thermal comfort is determined by distribution, stratification, i.e. layers, and air movement.
A clean slate Many care homes have low surface temperature (LST) radiators, which function like normal radiators but have a protective cover to prevent scalds.
However, the covers can create maintenance and repair issues as they can be damaged by challenging behaviour and may also need regular deep cleaning as the ingress of fluids and solids may harbour infection and create odour. The bulky covers may also reduce
usable wall and floor circulation space as well as providing potential impact points in the event of a fall. However, the issue that is most often overlooked is the effect that covers have on performance and energy efficiency. Simply placing a shelf over a domestic
radiator can reduce performance by up to 30 per cent as radiators rely on convection currents, i.e. air movement, to distribute heat. Encasing them in a protective steel
shell not only blunts performance by up to 80 per cent, but can restrict cooling air flow so much that the surface temperature is no longer low. Given that the heating system may
have to be operating at 80°C to achieve the required heat output, this is a significant waste of energy and may in certain circumstances negate their LST safety credentials. As a result, it is perhaps no surprise that many care homes and assisted living schemes now opt for underfloor heating.
Underfloor heating Laying heating pipes in the floor certainly takes away the impact hazard and hygienic concerns that relate to the use of LST radiators, but what about thermal mass? Thermal mass is a term used to extol
the virtues of under floor heating and how it can continue to enable heat energy to be emitted after the heat source has stopped providing heat. It is sometimes claimed that this thermal inertia actually saves energy as the heating system just ‘ticks over’ rather than ‘revving up’. The claim is used to rationalise a
fundamental issue with thermal mass heating systems – response times. Being embedded into the concrete means that it takes more time to reach a certain temperature and considerably longer to cool than conventional radiators. Various complications such as
weather compensation and computer predictive controls can mitigate the effect, but the stark fact is that due to our fickle climate under floor heating is often on when you would rather it was off and vice versa. Imagine two cars - one is small and lightweight, while the other is a
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www.thecarehomeenvironment.com• February 2021
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