Green Building Forum - Heating with wind turbine

Heating with wind turbine

CWatters — Wed, 13 Mar 2013 22:20:46 +0000

Any advice for this poster on another forum? In particular how to meet SAP when using the output from a turbine to drive an immersion heater. Is the SAP assessor correct?

http://www.ebuild.co.uk/topic/11828-advice-needed-please-re-heating-with-wind-turbine/

Quote:

The SAP assessor has just informed us that the house will fail as it stands, because of using an immersion heater. It would only pass if we either installed an air source heat pump or:

To enable the dwelling to pass using electric space/water heating the following would be required:â€¢Electric under floor heating throughout

â€¢Electric instantaneous water heating

â€¢100% low energy light fittings

â€¢Pressure test at 3.8

Heating with wind turbine

DarylP — Thu, 14 Mar 2013 09:21:59 +0000

CWatters,

As them to email me, I have Dip. OnConEA, and am happy to help where I can.

Cheers

Heating with wind turbine

Ed Davies — Thu, 14 Mar 2013 10:19:29 +0000

I'm expecting to have similar problems. My current plan is to install the smallest possible LPG system boiler which will keep the regulators happy and probably be a good fall-back for the odd periods when my solar (plus small turbine?) aren't sufficient. Hopefully a 47 kg bottle should last a while in practice so no need for a big installed LPG tank.

Don't understand why an immersion isn't allowed but electric UFH is. Can't be much difference if the heat leaking from the tank goes into the house.

Heating with wind turbine

DarylP — Thu, 14 Mar 2013 13:33:12 +0000

Both are 'allowed', but electric space heating pushed the DER up massively, so the designer has to compensate with increased thermal performance to reduce the space heating load.
SAP is primarily a CO2 reduction tool!
Mains electricity is the most CO2 intensive fuel type.

Good luck

Heating with wind turbine

Ed Davies — Thu, 14 Mar 2013 13:52:57 +0000

Well yes, but why does an immersion push the DER up but electric UFH not? What's the difference?

Heating with wind turbine

DarylP — Thu, 14 Mar 2013 14:21:50 +0000

.... possibly an error in the assessment?
It is very difficult to comment on something I have not seen?

Perhaps the Fabric losses are so small that the electric ufh will not use that much electricity, whereas no amount of insulation can reduce the hot-water energy requirement...?

Cheers

Heating with wind turbine

joe90 — Thu, 14 Mar 2013 22:37:55 +0000

Really good to see JSH giving sound advise on this other forum, their gain, our loss IMO.

Heating with wind turbine

Ed Davies — Fri, 15 Mar 2013 09:39:30 +0000

Not sure but it looks to me like JSH is muddling up ACH and mÂ³/(mÂ²Â·h) over there. oz07 picks up on it further down the thread.

It's more than a little irritating (to me, at least) that a) there are these two ways of measuring things, b) people don't make it clear which they're using and c) the stupid mÂ³/(mÂ²Â·h) measure exists at all as it fails to encourage designs with small outside surfaces. If it was mÂ² of finished floor area rather than envelope area it'd make a lot more sense (to the limited extent that floor area can be taken as a proxy for occupancy). Ditto specifying element U-values rather than the building heat loss coefficient per mÂ² of floor area.