Another house building project.

[adam2]

By friends of mine, NOT MYSELF.
Has been touched upon elsewhere in these forums, but worthy of its own thread. Housewarming party any day now.

The basis design and construction was already decided upon, my input was regarding the electrical installation and heating etc.

External walls are local stonecast blocks, with an inner leaf of concrete blocks for cheapness, strength and thermal mass. Internal walls are partly cob and partly reclaimed materials. Huge thermal mass.

4 PV systems installed, 3 are grid tied, one for each phase of the three phase mains supply. And one for battery charging. No generator.

Space heating is from a small multi fuel stove for the main living area. The central chimney should give slight warmth upstairs.
Cooking is electric in summer with a log burning AGA type cooker for winter.

Full HVHR throughout. Not working very well at present because it recycles heat, and you to HAVE some heat in the first place to recycle. The electric heater in the fresh air duct is running 24/7 and consumes 4 kw.

At present the house is uncomfortably cold and not very satisfactory. Space temperatures in main living area only 19 degrees with a good fire, drops quickly to 15 degrees if the fire goes out.
These low temperatures are, I hope due to the great thermal mass taking a long while to warm up.
An LPG light is being used to extract the last bit from loads of nearly empty propane cylinders, and adds some heat.

Hot water is electric, largely from surplus PV.

[clv101]

Is there still damp in the concrete, plaster etc? It took our place a year to be fully dry.

How much PV in total? May find there's enough electric good for winter cooking.

[kenneal - lagger]

Do they know how air tight the building is? If the house is leaky it will take a lot of heating.

[adam2]

Yes I suspect that there is still damp from building work, and a lot of cold thermal mass.

All four PV systems are the same size just under 4 kw, three grid tied and one battery charging. The battery charging system heats hot water when the battery is full is it almost always is.

[BritDownUnder]

I found this useful link on thermal mass. I have no knowledge in this but from watchin "Grand Designs Australia/NZ" I do recall they said it took a year or more for the cob/mud to dry thoroughly. Until then a lot of heat is probably spent in evaporating the water.

Insulation is probably a consideration. After all if you lived in a cave, with infinite thermal mass, in the UK, the average ground temperature is between 12.7 degC and 8.8 degC depending on location/latitude and if your walls/floor are a good heat sink to the ground then that is what you will equilibrium to until you set up a temperature gradient in your walls. Was there insulation between the inside and outside layers of the exterior walls?

Let's hope they have some big South-facing well glazed windows to take advantage of passive solar energy.

Another thought... It may be worthwhile taking the temperatures of the walls at various points, either by contact thermometer or IR heat gun and trending them over time to see if they are warming up. Nothing like scientific method.

[adam2]

A large industrial dehumidifier has been purchased secondhand and is helping considerably.
The external walls have a well insulated generous gap between inner and outer leaves.

The small multifuel stove is being run on anthracite, reluctantly as logs are scarce and expensive and a local supplier has anthracite on special offer.
Coal burning also needs less attention, refueling three times a day rather than every couple of hours.

(They have a vast supply of logs, but freshly cut not dry enough for at least another year, two years would be better)

[adam2]

Living room now at about 22 to 24 degrees, with the stove lit continually.
Rest of the house still a bit cold but slowly warming up. Electric heat in the MVHR system still used a lot but not continually. The fresh air supplied from the MVHR is at about 20 degrees without the electric heat and about 22 degrees with electric heat.

[kenneal - lagger]

It would be worthwhile having an air tightness test if they haven't had one done yet. It will pinpoint any leakage which can then be attended to.