Different heating systems in Care Homes
What’s THAT all about?
The Care Home Sector is especially vulnerable to rising energy costs.
The care home sector is undergoing tremendous changes and restructuring, and is uniquely vulnerable to increasing running costs including heating.
Recent changes to building regulations and the introduction of SAP in 2005, have all contributed to the headaches operators face when seeking to comply whilst undertaking new build or refurbishment projects.
The amount of misinformation and bold claims in the green-building sector seem to rise in direct proportion to the oil price. So what are the facts, and what options are available to Care Home operators & developers apart from the usual suspects – radiators and under floor heating?
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The first law of thermodynamics is that energy can neither be created nor destroyed – just changed from one form to another.
So, if we cannot create energy or destroy it, how do heat pumps work? Can they really save you ‘75%’ of your energy bills. Well, yes and no. Yes if you’re barking and run the entire property on peak rate electricity, no if you’re on mains gas.
The magic number for heat pumps is a COP (Coefficient of Performance) of 4. Why 4? Why not 3? Why not 7? Why not PI? (3.142 since you asked). This means for every 1kw of electrical energy consumed by the heat pump, you create 4kw of thermal energy to heat the house. But why 4? Well, it isn’t often discussed, but 4 is a handy target as electric is about 3~4 times the price per kw/hr than gas. (Just check the back of your latest bill; it averages 3.2p/kw.hr for gas and 10.7p/kw/hr for electric)
Well… the inconvenient truth is that at the end of the day, rooms aren’t occupied by sensors or monitors, but by people, (and older people are especially sensitive), so the results are open to ‘interpretation’.
As a result of real people actually being in the room, a factor known as ‘Thermal Comfort’ comes into play. Researched by a boffin with the fantastic name of P O Fanger in the 70’s, this details the complex relationship between man and his thermal environment with sections on air temperature, air speed, humidity, mean radiant temperature etc.
As a result, it’s the thermal comfort that is more important to the occupier than the actual thermal output, and thermal comfort is determined by distribution, stratification (layers) and air movement.
Under Floor Heating – too hot for some
Going back over the debate that “if a room needs a Kw of heat energy, how can any system that delivers a Kw claim an advantage over the other?” Have a look at the 2 images above. One shows the heat distribution achieved by a typical convector radiator and the other by a radiant heat source with even distribution. Both systems are emitting 800w of energy; the amount of energy required to heat the room according to the heat loss calcs.
The mean average temperature of the 4m x 4m room with 2 external walls and a window measuring 2m x 1m was 18.2°C with a radiator, and 20.2°C with the radiant heat source.
That’s 13% better! In other words you would need to turn up the heat output of the radiator by at least 20% to match the radiant heat source emitter.
The radiant heat source is Under Floor heating, right? Wrong. It’s Thermal Skirting.
Thermal What?
You heard; Thermal Skirting. It’s a radiator in the true sense of the word, but built into an exact replica of a skirting board. Being all around the room at low level, it heats the room just like under floor, but much quicker and much more responsively.
Being above ground, it can be retro fitted into existing as well as new build, and can connect onto existing conventional systems as well as renewables such as heat pumps and solar thermal systems.
These are designed to run cooler, and to distribute the heat evenly all around and so retains the aesthetics and colours of traditional skirting.
And it’s catching on.
But What About Thermal Mass?
No, its not a Rap singer, it’s a term used to extol the virtue 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’s sometimes been 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 of the slab, means that the time to come up to temperature and to cool is considerably longer than with conventional radiators or thermal skirting. 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, UFH is often ‘on’ when you’d rather it was ‘off’ and vice versa.
Is that really energy saving?
Oversize Radiators – The Solution?
In many new developments, the introduction of a heat pump is seen as the green tick in the box but to offset the higher costs compared to a condensing gas boiler, steel panel oversized radiators are used – job done!
Well, maybe. Radiators are mainly convectors (move air) and rely on thermal currents to distribute the heat around – and then not very well (see diagram 5). When operated at even lower temperatures of 40~45°c the thermal uplift they create is greatly diminished. Result? Micro-climating. What? Did I just make that word up? Well yes, but not just, as it perfectly describes what happens at lower operating temperatures. The warmish air cools rapidly and falls close to the emitter - to be re-heated and rise again. The heat distribution pattern is very poor and even though the radiator might be supplying enough heat energy according to the calcs, the cold spots will be bigger than on an Eskimos’ bum. The only way to ensure an even comfortable environment for the occupant would be to fit more of them around the room. Nice!
Cost Saving Installation & running costs
Being the skirting as well as the heating, the hidden savings of fitting both at the same time are not lost on developers (yes, there are a few left) and when timber construction is used, the advantages over under floor heating are obvious.
Plus, as it’s above ground in can work with any floor finish including carpet & timber, and can be adapted and amended.
Thermal Skirting may not solve every heating problem – it doesn’t heat the tile or marble flooring underfoot – but it can be readily retro fitted into virtually any property, including public spaces such as schools, hospitals, care homes and hotels. With more than 24 million existing properties in the UK, (8 million with decrepit, inefficient or no heating system at all), and far fewer new ones being built thanks to Fred Goodwin & friends, the real target for lowering CO2 emissions has shifted focus.
Tackling climate change by installing energy efficient heating systems and emitters such as thermal skirting into the existing housing stock has just become a whole lot easier.
Summary
Both British Gas and ‘BRE’ have published reports which indicate that gas condensing boilers demonstrate up to 2% savings when operating at 50°c or less.
Similarly, renewables such as solar and heat pumps work best and most efficient at lower temperatures, but can also provide higher outputs if the immersion heater kicks in. As design temperatures account for the worst 9 days of the year (the average days per year is -1°c) means that systems such as Thermal Skirting can provide sufficient heat at lower temperatures for the majority of the year, and still work at higher flow temperatures during these average 9 worst days – something that will be required for updating older buildings that don’t have the latest insulation.
2010-08-27 14:57:31
