Fixing the damp and reducing the heating bills

Dampness

The dampness problem should not be exaggerated. There are only two rooms that have damp problems. Room B on the as built plan (which was the headmaster’s office) is very damp indeed, certainly uninhabitable. Room C is very damp on the west facing wall, the wall with the large window looking out over the car park. We think this dampness has two causes:

The solid brick walls were built between the wars and should almost certainly have a damp course formed by several layers of engineering brick. This should have made the room dry but unfortunately layers and layers of tarmac on the road outside seem to have breached the damp course, see picture below. If this damp course isn’t present, then we could cut and insert one at a reasonable cost.

The other problem seems to be penetrating damp up the south-facing wall and this can probably be explained by the poor condition of the outside render.

Fixing the heating bill

We’ve taken measurements of all the walls, roofs, floor areas, doors and windows and produced a spreadsheet that calculates all the heat losses of the building. All of these calculations follow Part P of the Building Regulations. Our calculations show that the present building should cost about £10,000 to heat each year – in the same ballpark as the actual costs.

Next, we then recalculate this heat loss if we apply various levels of insulation. If we add loft insulation, floor insulation, apply external insulation to the walls (which fits nicely with curing the penetrating damp problem), bring the windows up to a modern double glazing standard and heat the building using a heat pump/borehole combination, then the heating bill falls below £1,000 per annum. The following calculations are for an internal temperature of 19 ºC, the figures for -5 ºC give us an idea of what is the maximum load; 9.5 ºC is taken as the annual average temperature for Anglesey.

Overview insulation levels Outside air temperature Heat loss rate (watt) Annual electricity consumption (kWh) Annual running cost with heat pump (Cop=3)
As found -5 55,945    
  9.5   193,988 £9,699
Intermediate -5 12,351    
  9.5   42,847 £2,141
Best -5 6,668    
  9.5   23,123 £1,156


The redesigned buildings shown on the next pages will have lower operating costs because there is a slight reduction in floorplan area. These estimates should be regarded with caution. They are quite often wrong and here we haven't allowed for the heat lost through air changes. However, it is doubtful that we will ever operate the hall at a temperature as high as 19 ºC.

As a consequence of these two actions we will convert the building to one with very low maintenance and heating cost. Then it doesn’t matter so much if there are times when utilisation is low because the financial loss each year, per room is small.

We have an estimate for applying the required external insulation, installing insulation beneath the floors, installing under-floor heating, and installing a heat pump of just under £200,000. There’ll be more work required, but this does indicate that a refurbishment project is worth further consideration.

New designs using the old school buildings