Part L and its predecessors have been around for ages. The change in
2002 was to reduce the standard U-value for walls from 0.45 (which you can achieve with brick/unfilled cavity/125mm lightweight block) to 0.35 which generally does need cavity fill. It's quite possible though that an pre-2002 regs house was built with cavity fill to allow the use of a cheaper block.In message , Mark writes
you seem to have missed the 'Even if you're not eligible for FREE insulation, we can still offer great discounts on your installation'
for us, having 90 m^2 of loft insulation (topping up the patchy and thin existing stuff with another 250mm of fibre glass) done via Npower cost us £296.00 - there was a grant element of 127.00.
This included draft-proofing the loft hatch, insulating pipes, and 3 CW tanks (we had to pay extra for 2 of those as the grant element only covers 1, ditto we had to pay extra for 10 m^2 of insulation as the grant only covers up to 80, but we have a big loft area - that covered £75 of the cost).
A quick Google up suggests that it would have cost us more in material to DIY anyway, let alone having to do a horrible job
Often they use "cavity wall batts" for that - can be full fill that take all the cavity and are made from rockwool or similar. Or they can use a partial fill of a PIR foam like celotex. This is a ridged yellow board usually covered with foil on both sides.
The 2000 regulatins were very exacting insulation wise.
Its a con.
Total crap. I built my house to 2000 regs and it is incredibly insulated. They wouldn't let me do anythng else.
The Natural Philosopher coughed up some electrons that declared:
Sorry - must have been windows I was thinking of...
But it's virtually impossible to reach the U-values required without some form of additional insulation in a cavity wall construction. Even with the best aerated concrete block, the best U-value will be about
0.7W/m^2K. This is the upper limit for any _part_ of a wall; the average must be no more than 0.35W/m^2K, and in reality for a conventional spec-build volume housebuilder to to achieve a DER anywhere near the TER, the walls would need to be somewhere around 0.25-0.28W/m^K.Of course, if you're building a house that will have Kevin McCloud crawling round it, then you can make use of biomass boilers, sun-spaces, photovoltaic cells, etc. to reduce you carbon emissions to the point where it doesn't matter how much heat the walls leak. I just can't see it being built by Persimmons or Barratts.
When you say the house was built in 2001; was this closer to the start or finish of the estate? With any change in requirements, there is a lag between when the initial notice was given to the Council, and when the building was complete, and this can be up to three years from deposit to starting the work, and then as long as it takes to complete. The rules on this have tightened up in the last decade, but a big client for the NHBC can still get around this.
Up until about 1995, it was possible to achieve the U-values without cavity wall insulation by relying on a mix of double-glazing and aerated concrete blocks. In 1995, U-values were lowered (better), and I don't recall seeing any houses or extensions built to these or later requirements without some form of cavity wall insulation.
Cavity wall insulation is either built-in during construction or injected after. Built-in types are mineral-fibre batts (Rockwool) which fully fill the cavity, or partial-fill types such as expanded or extruded polystyrene (white, pink or blue boards) or polyisocyanurate or phenolic foam (Kingspan, Celotex, et al - usually dull yellow with foil on both sides). These leave a residual cavity of between 25mm-50mm. Injected insulation is either loose mineral fibre (white or yellow), foam (which sets solid), or polystyrene beads.
You may be able to see evidence of the cavity insulation (or lack of) around service penetrations (meter cupboards, badly-sealed gas pipes, etc.), or at the head of the cavity in the loft.
Even if you have partial-fill insulation in the cavity, you shouldn't go injecting any more. Partial-fill insulation isn't designed to prevent water tracking across it, and rely on a residual cavity to keep the inner leaf dry.
However if you do have a clear cavity with aerated blocks, you can still benefit from cavity insulation. It should lower the U-value from about
0.7W/m^2K to 0.35W/m^2K, reducing the heat loss through the walls by half.
A clear cavity/ aerated block wall only achieves 0.70W/m^2K, according to my Elmhurst U-value calculator[1]. Which, IIRC, was less than
0.6W/m^2K without thermal bridging that came in in 1995. This was only acceptable up to then, as I never saw a wall that needed a U-value of 0.45W/m^2K without insulation. [1] Horrible interface. Bring back SuperHeat!
Couldn't possibly comment . Let's just say that no one could accuse the Elmhurst team of copying anyone else's design ideas. We had no option but to give up SuperHeat because of the new EPC rules: I did point out to DCLG the year before that the effect of these would be to effectively leave the Part L software business in the hands of a few larger players.
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