Commentüs on: SAP and CHP - a dangerous muddle?

By: CHP and SAP - part II « carbon limited

CHP and SAP - part II « carbon limited — Thu, 20 Mar 2008 21:33:43 +0000

[...] an update on the way building regs for housing treats CHP. It’s not as simple as I thought here, although the result is similar. The incorrect method I wrote about a few weeks back is still in [...]

By: emissions from CHP: the standard method is wrong « carbon limited

emissions from CHP: the standard method is wrong « carbon limited — Mon, 04 Feb 2008 21:32:00 +0000

[...] from CHP: the standard method is wrong I’ve written on this topic before but I don’t think I succeeded in making clear just how far off the mark the standard [...]

By: Carbon Trust micro CHP interim report finally out « carbon limited

Carbon Trust micro CHP interim report finally out « carbon limited — Tue, 27 Nov 2007 18:28:51 +0000

[...] is. In summary, micro-CHP saves 5% to 10% of carbon in large inefficient houses but only if you use SAP’s flawed methodology and give yourself extra-extra credit for displacing grid electricity. A few of the key [...]

By: Casey

Casey — Tue, 20 Nov 2007 08:57:13 +0000

Thanks Mel. Nick did a quick check in NHER and confirmed that this is indeed what SAP is doing.

I sympathise with your conflict of libertarian vs. cynic. If you want to get a clear idea of how CHP is going to perform on a given site you need a lot more a few cells in a SAP spreadsheet can provide. So either you publish a standard assessment procedure just for CHP (which includes things like hourly demand profiles) or you let engineers get on with it themselves. Maybe CHP Sizer could be adapted for this? It’s quick and simple but gives a much better idea of actual performance, though it doesn’t currently do residential.

By: mel starrs

mel starrs — Mon, 19 Nov 2007 22:14:45 +0000

Nice analysis. Unfortunately I’m miles from software which could help verify your results, but from my previous experience, I suspect you’re right. I once got a bee in my bonnet about the previous Building Regs and SAP, especially regarding electric heating. I even had an article published in BSJ, but I doubt it was even noticed. Sigh.

The libertarian in me is beginning to think the government should start to leave the calculations to those who can do them rather than imposing random targets which have been picked from thin air. But then the cynic in me thinks that targets are necessary to rein in the greater excesses of money spinning developments. Yikes, I’ve gone all philospohical.

This all points to something which I’ve been mulling over about the role of BRE, government departments and CIBSE within the industry. How much independence they have, where they get funded from, etc…