Electric Radiant Heating
Why consider electric radiant heating?
There is no getting away from it – using electricity to heat your property is expensive. I hope that this page will give you ideas to assist in keeping the cost of electric heating down.
First thing to state is that electric heaters are efficient – even the old fashioned thing shown below is 100% efficient – literally all of the energy put in comes out as heat. 1kW in = 1kW out.
For me the key element is what I call “energy effectiveness” and in this respect not all electric heaters are the same.
One of the more effective systems I have found over the years and have specified for installation in clients’ properties has been ceiling mounted ‘long wave’ radiant panels that pretty much replicate the sun in providing gentle comfort where conventional systems struggle – “hard to heat” properties if you like – churches, school halls, shops with open doors, garden centres – anywhere that heating the volume of air is not practicable. I installed many hundreds of these heaters in Moray Council schools during the late 90’s into the noughties and Greggs (the bakers) used them to replace energy intensive air curtains in many of stores. Interestingly they used them inside the shops as well sometimes because the heat output appeared to have no impact on fresh cream products on display below.
This type of electric radiant heating was developed in Sweden and works by replacing the human body’s heat losses to moving air.
It’s akin to moving from the shade into the sun on a nice sunny day – the air temperature doesn’t change but the long wave radiant heat of the sun replaces your heat loss to moving air.
As a result you can place these heaters in a wind tunnel and as long as you are within their sphere of influence you’ll be comfortable.
What do they look like?
Generally this type of electric radiant heating is fairly “industrial” in appearance – although I have been involved in a couple of installations where the heaters were painted black or dark brown with exhaust manifold paint capable of withstanding >600oC and the result in a church with a dark wood ceiling was very impressive – rendering the heaters virtually invisible.
Electric radiant heating operates at very high surface temperatures – usually well in excess of 300oC which means you need to get them out of harms way – out of reach. The benefit of this is that they effectively heat the occupants of a treated space up to 18m below the mounting height.
Electric Radiant Heating Panels
These heaters are also supplied as simple white panels (600×600 or 600x1200mm) designed for lower ceiling – I actually have some in my own office at a height of 2.1m. In this form they are capable of providing very gentle warmth (surface temperature 70-90oC) and are suitable for offices, nursery schools, nursing homes, primary schools etc.
These heaters are generally 300W or 600W and they can be surface mounted or recessed into suspended grids. The heaters are almost invisible – see if you can spot them below
How many do I need?
Electric radiant heating is generally designed for a space on the basis of square meterage as opposed to volumetric heat loss used to calculate requirements for conventional air heating systems.
Worst case scenario – an uninsulated, draughty, church hall with a vaulted ceiling and single glazing – you are looking at 350W/m2.
Well insulated office with double glazing – like my own office – 32m2 heated by 2.4kW (4 x 600W panels) works out at 75W/m2 and I have to say that I am glad I zoned my office into two sections because most of the time I work with just heaters during the winter which is 37.5W/m2.
But here a note of caution is required. Electricity is not a cheap form of energy.
A church for example with a main hall measuring 25mL x 12mW and 7m ceiling height might require 105kW heat input (25 x 4.2kW electric radiant heaters) and if the heating is operated for 3 hours to cover 1.5 hours pre-meeting warm-up and 1.5 hours during the meeting then 315kW of electricity could be used which might cost £50 (based on 15.9p/kWh which is not uncommon).
So you need to know what your operating hours are likely to be, what your electricity costs are (p/kWh) and then work out what your options are.
Electric radiant heating is not a panacea – but it can be a very useful solution.
Control over heaters – and particularly electric heaters – is paramount to achieving “efficiency” as most people envisage it.
Control over the people using the heaters is also essential to ensure they heaters are not left ON in empty spaces or remain ON when windows and external doors are open.
It is also useful to educate occupiers of buildings as to what represents a reasonable space temperature in which to operate. I have visited offices where the temperature was in excess of 28oC and occupiers were still “feeling a bit cold” – this is not appropriate behaviour or expectation but it is not uncommon. Staff Awareness is everything.
I have many years experience specifying these systems:
- determining when they are suitable and when they are not,
- ensuring controls are commissioned and maintained,
- educating occupants of the treated spaces.
If you are stuck with electricity as your energy form for space heating get in touch and let’s look at all the options available to you – I have no ties to any supplier and offer impartial, independent advice to allow informed decisions for optimum solutions.
Electricity doesn’t need to cost the earth!