100 year old house - C2 rating

derickmc · 08-03-2009 11:44AM #1

I have just assessed a house built before 1900. The house has an extension built in 2002.

The 2002 extension counts for about a third of the over all floor area.
The house is mid terrace and as it is deaper than wide the majority of its walls are unexposed. Half of the walls that are exposed are part of the 2002 extension and therefore well insulated.

There is a 78% efficient combi boiler.

There's no secondary heating system.

Cat 2 heating sys, room stats & motorised valves.

All chimneys are blocked (permanently). There is only 1 vent in the house so not much heat lost there.

150mm attic insulation.

The exposed perimiter of the old uninsulated is floor is 0.1 giving it a u-val of .27

Double glazed windows.

The rating comes out as a C2. I have reviewed it several times and I am quiet confident of my abilities. However is seems odd that a house of such vintage could obtain a C2 with out some wall insulation.

Any thoughts. Anyone assessed a similar house?

Thanks,
Derick

sinnerboy · 08-03-2009 12:46PM

Your client is off to a good start with the party walls not deemed heat losing elements
Then in the case of the 1900 front elevation - tended to have small % glazing - which you say is now double glazed.

The rear elevation is now enclosed with reasonably good insulating construction and a good level of mech spec ( ok boiler , good controls )

So C2 does not surprise

You could "play" with it - copy your DEAP file and see the rate plummet if you pretend the house is detached

Count in the party walls as heat losing .
Then pretend they each have 15% glazing
Remove the heating control
Assume 60% efficient boiler

Watch the affects with interest

NB - the house is not ventilated to b regs requirement - min 5000mm2 to all habitable spaces . You should advise the cleint of this and inform them how this will affect ( degrade) the BER rating

Going towards 100% LEL
additional 150 attic ins
will compensate

.

sinnerboy · 08-03-2009 01:50PM

There is a big risk of interstitial condensation if one attempts to achieve new house current regs u values when dry lining for old buildings

Note that - TGDL 2008 requires only 0.6 and the UK Energy Saving Trust - recomends 0.45 as best practice for dry lining .

Read carefully

http://www.energysavingtrust.org.uk/uploads/documents/housingbuildings/ce97.pdf

.

derickmc · 08-03-2009 05:44PM

Thanks sinnerboy,
I have been messing around with the rating alright. I also opened another assessment of a similar age house which had a G rating and applied the improvements that this house has and it brought it to a D1. The house I was experimenting with had a smaller extension by increasing the size of this and bringing its year of construction to 2002 brings the rating to a C2. I am happy now that I haven't missed anything..

100 year old house - C2 rating

Comments