“The principle of electrical under-floor heating consists of warming the surface of the floor by embedded cables resulting in a gentle and generalised radiation.”
“The use of floor heating by electric cables of a type which are virtually indestructible eliminates pipes, radiators, equipment, boilers and mechanical plant.”
Chamberlin, Powell & Bon, Architects “Barbican Redevelopment” April 1959
Officially, under-floor heating is switched on from 1st October to 30th April. But the Barbican Estate Office are flexible about this if there’s a cold spell outside those dates.
Electric cables in the floors maintain a background temperature of 15.6°C (60°F). Guidance in the past has said that if the outside temperature drops below 1.7°C (35°F), the internal temperature may fall a bit as well. But, in fact, I understand that the system adjusts the charge needed to maintain the desired temperature, based on the actual external temperature at the time. So it is flexible and responsive to actual conditions.
Apparently, the type of flooring or carpet may affect the temperature in the flat.
The heating does not come on at exactly at the same time right across the estate. There are three different groupings of properties, but they come on at more or less the same time.
You don’t have any individual control of the system for your flat in the basic system. You may need your own top-up heating (especially when Spring declines to arrive on 30th April). I understand that some flat owners in some blocks have had an engineer remove a fuse to turn the heat off just in their bedroom.
But there is a more sophisticated system, which is that you can install a ‘trimmer’ which can regulate the background heating for the flat as a whole, or be used to isolate individual rooms from the background heating system, or change the times during which heating is on. These steps need to be taken by a qualified electrician. Otherwise, the only way to lower the temperature is by opening your windows!
The under-floor heating uses cheaper off-peak electricity. You don’t pay for it separately. The overall heating cost of your building is part of the service charge.
Heating is supplied by cables placed in the floor screed when the floors were laid. The screed is 70 mm deep, and the cables lie in the bottom 12 mm of the floor screed on an insulating quilt of ethylene/propylene material. This means that 70% of the heat is emitted upwards to your flat, and 30% is emitted downwards. On the ground floor, the thickness of the screed was increased to 115 mm with an insulating layer of expanded polystyrene 38 or 50 mm thick to minimise downward heat loss. (There is an insulation quilt in the floors to prevent heat loss from the under floor heating system. This incidentally adds considerably to the sound insulation of the floors against noise from neighbours.)
Maintenance and damage
The Barbican have to maintain your system, so report any problems to the Barbican Estate Office.
Beware the dangers of carpet fitters putting a nail though one of the heating coils. Your floor will have to come up if the Corporation have to mend it and they will bill you for the work.
A heater in the bedroom cupboard
A conduit was installed from the main supply to one of the bedroom cupboards to allow for a heater to be wired in. This would then be wired through to a switch next to the main consumer unit.