Is current Part L the optimum standard for houses?

Post by **kenneal - lagger** » 09 Mar 2010, 02:32

I was told in the pub after Ecobuild by a CAT MSc course member that the current Building Regulations Part L was the optimum insulation standard for houses and that my espousal of the Passivhaus insulation standard was wrong.

Would anyone like to tell me if, and why, I am wrong, please?

biffvernon · Post by **biffvernon** » 09 Mar 2010, 07:05

I'd be interested to know why the pub talk led that way.

I'm not sure that there can be a 'optimum' as so much depends on building usage and other factors.

contadino · Post by **contadino** » 09 Mar 2010, 07:39

Pasivhaus levels of insulation means that the house is pretty much airtight if I understand it correctly. Whilst this is all well and good in terms of retaining heat and consequently reducing heating fuel, I don't think it's a particularly healthy environment to live in. Of course, there are loads of experts flogging gadgets to alleviate stale air problems, but it does complicate a build considerably.

I voted for option 2, because it should be standard practice in northern Europe to build to pasivhaus standard, but people need to take into account air circulation from the design stage.

mobbsey · Post by **mobbsey** » 09 Mar 2010, 10:43

kenneal wrote:I was told in the pub after Ecobuild by a CAT MSc course member that the current Building Regulations Part L was the optimum insulation standard for houses and that my espousal of the Passivhaus insulation standard was wrong.

Consider this conundrum: A half-timbered Elizabethan (the 1st!) home has a fraction of the energy and carbon footprint of a modern home, and was the standard at a time when average temperatures were 3 to 4 degrees colder than today -- but there's no way they'd pass Part L!

Standards are not as important as the expectations that those standards are designed to fulfil, and at the moment it's our expectation that do not accord to the reality of the future energy scenarios, not the building code (sorry if that's all a bit Zen, but it seems that at the moment the eco-debate is talking about anything other than the obvious problems at hand!).

biffvernon · Post by **biffvernon** » 09 Mar 2010, 11:34

Post by **kenneal - lagger** » 09 Mar 2010, 14:50

Biff, the person concerned walked up to me and said that they thought I was wrong because they worked on office design and they usually had a heat gain problem! I did point out that that situation is not normal in the housing sector but they stuck to their point and said that they could win a debate on the subject at any time. I think that they just wanted to have a go at "the smug old git." I've initiated this debate on the CAT student website as well but I thought it might be interesting to have it here.

I say that Passivhaus is the optimum level of insulation because if you start putting more insulation than is required by the PH standard into a house in Northern Europe you are getting into the region of not getting the embodied energy in the insulation back from the installation over a reasonable lifespan. To halve the insulation value of the installation you would have to more than double the insulation thickness so to go from the U-value of 0.14, given by the approximate 300mm of insulation in a wall, to 0.07 you would have to install 600mm of insulation. Not worth it.
It's the exponential thing again; getting to the point on the graph where the doubling kicks in and the increase goes rapidly skywards.

With Passivhaus insulation there is no space heating required for much of the year and if heavy weight construction is used a good carry over of heat is available for cooler days and cool for warmer days. Energy poverty is almost eliminated with Passivhaus as is a central heating system. A small room or air heater is all that is required.

While we have the energy to build and refurbish to these standards I believe we should do that. If we have to use oil based products to do it, it is a better use of oil than burning it. Using oil for insulation sequesters its CO2 in the building for the life of the building, 200 to 300 years or more, and saves energy over all that time.

The Elizabethans only built to that standard because they used the best technology of the time and that was what you got. They didn't, for example, have the benefit of cheap glass. Neither did they have kiln dried, engineered wood to make draught proof windows and doors. A modern Elizabethan oak framed house can be built to Passivhaus quite easily. I had just such a project finished recently, although the client didn't go to full PH. With our current population we couldn't heat our houses sustainably if they were built to Elizabethan standards. With PH we could.

PH doesn't entail any stuffiness or lack of fresh air. The use of mechanical ventilation with heat recovery supplies the correct amount of warmed fresh air all the time. If you are willing to forgo the ultimate in energy saving, passive stack ventilation can be used instead which involves a much more robust system for the longer term future (the road I prefer) but with the penalty of the heat loss in the ventilation air. You still have all the benefits of the very high insulation levels, though.

biffvernon · Post by **biffvernon** » 09 Mar 2010, 18:11

Can't argue with that.

I guess the bloke in the pub was used to office blocks made out of glass with no user-openable windows. Much easier (though not cheaper) to heat in winter than cool in summer.

The Elizabethans (I) probably just got very cold in winter, wore lots of clothes and complained about chilblains. They knew nothing else.

I kinda feel I like to be a bit connected to the seasons and the weather, opening and closing windows when I feel like it and the storms dictate, rather than being separated by an MHRV system.

For sure there's laws of diminishing returns kicking in when you add more than the 'optimum' insulation.

ecoworrier · Post by **ecoworrier** » 09 Mar 2010, 20:04

By course member you mean student?
I have known two on that course.

"A little learning is a dangerous thing; drink deep, or taste not the Pierian spring: there shallow draughts intoxicate the brain, and drinking largely sobers us again."

It beats me why we went down the SAP route instead of PH.
PH has been tried and tested for years, but no we had to come up with our own.

PH is far superior method of designing houses, Part L is an ill-conceived bag
of shite.

phobos · Post by **phobos** » 09 Mar 2010, 20:30

An Office full of PCs throws out an awful lot of heat, cant really compare them to domestic situations.

ndon · Post by **ndon** » 09 Mar 2010, 22:23

name and shame ken?

Post by **kenneal - lagger** » 09 Mar 2010, 23:59

ecoworrier wrote:By course member you mean student?
I have known two on that course.
"A little learning is a dangerous thing; drink deep, or taste not the Pierian spring: there shallow draughts intoxicate the brain, and drinking largely sobers us again."

I don't know what their qualification is but I think they're an architect or technician.

It beats me why we went down the SAP route instead of PH.
PH has been tried and tested for years, but no we had to come up with our own.

PH is far superior method of designing houses, Part L is an ill-conceived bag
of shite.

SAP and Code for Sustainable Homes are funding streams for the BRE.

SAP is biased towards the provision of renewables so a full Passivhaus often doesn't get a high SAP rating and CSH is so full of non insulation options that absolute rubbish can get Code 4. Code 5 is better, but still not good, while Code 6 is the other way and very difficult to get for small numbers of houses because of the renewables requirement.

I'll wait to see if they have the guts to come out of the woodwork, Brandon. And thanks for getting me into the Youth Hostel: £15 a night including brekkie was good.

Post by **kenneal - lagger** » 10 Mar 2010, 00:12

biffvernon wrote:I kinda feel I like to be a bit connected to the seasons and the weather, opening and closing windows when I feel like it and the storms dictate, rather than being separated by an MHRV system.

A client finished a house that I designed for them three years ago just in time for that last hot summer we had. It was designed to an overall U-value of about 0.2, not quite Passivhaus but still good, with a dense concrete block inner skin for thermal mass.

I'd told them to shut the doors an windows on hot days and open them in the evenings to cool the place off. They asked me round to talk about another job one very hot day and I found them sitting, sweating, with all the doors and windows open at midday. They said they'd got every thing open because they liked a breeze on a hot day!! It wasn't a breeze, it was blast from a fan oven!!

I'd left my house at about 21C to go to theirs at about 30C. Madness!! And I couldn't convince them that they would be more comfortable shut up; they wouldn't even try.

biffvernon · Post by **biffvernon** » 10 Mar 2010, 08:27

But there's not many days in the year when that happens.

RenewableCandy · Post by **RenewableCandy** » 10 Mar 2010, 16:23

biffvernon wrote:

But there's not many days in the year when that happens.

Yet.

Post by **kenneal - lagger** » 10 Mar 2010, 22:53

RenewableCandy wrote:
biffvernon wrote:

But there's not many days in the year when that happens.
Yet.

Quite!

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Is current Part L the optimum standard for houses?

Is the current Part L the optimum insulation standard for houses?

Is current Part L the optimum standard for houses?

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