What's the target heat loss of the house (given passive heat sources)?

Thanks both
<blockquote><cite>Posted By: gravelld</cite>What's the target heat loss of the house (given passive heat sources)?</blockquote>

I hadn't defined one other than to generally improve comfort levels, use less fossil fuel and reduce bills. Should I be doing some calculations? Bungalow is roughly 14m gable to gable and 7m wide. Living room/kitchen gable end faces north, bedrooms/small sitting room gable end faces south facing garden.

<blockquote><cite>Posted By: tony</cite>New oil boiler, heat pump, air, ground or water source, my favoured potion would be to to for super insulated, fill cavities plus 2 to 300mm EWI going down to concrete foundations, 500mm quilt in the loft,

Heating pipes in the floor could start leaking soon due to corrosion of the presumed copper, many do after 50yrs.

Pay for insulation once no more heating bills, service, repairs or replacement costs. Worth considering in my book.</blockquote>

I clearly need to do more research but from what little I've read there seem to be mixed reviews re heat pump, with low rad temps. I got the impression I'd need a huge garden for ground source, we just have a wee bit more than the building footprint. I'll take a look at air and water. Are pellet boilers stoves etc worth looking at.

Copper pipes corroding after 50 years gives me something else to worry about!!. I've seen that they are in a hessian tube.

RE EWI/Cavity you may remember I had a drama with the virtually useless CIGA warranty re cavities, its mainly filled with mineral wool but south wall was extracted due to damp ingress.

I'm sure 2 to 300 EWI would be a smart move but unfortunately I have a narrow alley on one 14m side (east) so best I could achieve there would be about 50mm EWI and perhaps a little inside.

A roof removal and repitch with 1st floor accom is perhaps a possibility so could improve insulation and maybe solar gain at that at that stage.

Whats your thoughts please?

Long term green / low carbon solution is to replace Oil with an electric heating system (alongside a decarbonized grid - which is still a good 20 years+ away) in conjunction with heavily reducing heat demand.

A heat pump provides lower temperature hot water, hence the need for larger radiators, or better still an underfloor heating system.

LPG will slightly lower carbon emissions, but raise heating bills and also isn't long term sustainable.

So comes down to either reducing demand, and/or replacing existing heating system with a more efficient one and improving the controls whilst considering what can be done cost effectively for the longer term e.g. consider a hot water cylinder with regular boiler, with capacity therefore for solar hot water, or for a future heat pump at next replacement (targeted at 15 years time, by which time an electric heating system should be lower carbon).

What's better for the planet long term isn't however necessarily good for the pocket short term.

I agree with Tony and Tom, the better approach is to look at reducing heat demand, but I would say combine that with ensuring that any existing defects are addressed, external walls adequately protected against driving rain, rainwater guttering and downpipes as well as drainage provisions looked at and improved where necessary, ventilation provision considered and if needs be improved and if insulating, think about the junctions and minimizing losses / avoiding risks of surface condensation.

Posted By: zak99Are pellet boilers stoves etc worth looking at.

I don't like pellet boilers because they are expensive, you are in hock to the fuel suppliers more so than with oil (due to limited suppliers), pellets are a low density fuel so they have a high storage volume, unless you go automated (expensive) there are daily routines to go through and even with automation there are the physical tasks of cleaning.

The above comments about insulating to the point that heating becomes almost irrelevant are correct but need tempering with actual possibilities of a retro fit (e.g. your limited access to one side)

It will be easy to negate any benifit of EWI if the cavity issues are not solved.

The cost of internal insulation is not much different if you have a little or a lot. If you can sort out the cavity and with 5cm of EWI then I would suggest the little IWI would not be worth the effort.

GSHP can be done vertically (drill down) but not worth the expense.

ASHP I don't know what the noise levels are on modern units - something to check, as would any upgrade to the electricity supply that may be needed. Also air to air or air to water? moving heating air will have some noise in the house.

On balance I would suggest insulate as much as reasonable / practical, replace the oil boiler with a modern one rated for the new insulation standard, DHW either off the oil boiler or electric E7. Consider PV and no mention yet of MVHR or PIV to manage the air tight post upgrade property.

Posted By: zak99I was hoping EWI would mean I could forget the gap in cavity fill. 80% of it is filled with mineral wool but the rear south wall is empty now.

You can't forget the cavity !! If you have a howling gale blowing through the cavity then this will nullify any advantage of the EWI so to get any benefit from EWI the cavity must be well sorted

Even so there is still likely to be draughts in the cavity and convection for sure.

In theory there won’t be any draughts but in practice they will get there and the resulting heat losses are not nice.

I agree - for most purposes - but if for instance making external render your airtight layer (and doing that so it works) and all EWI and EWI-like over-rafter insulation leaves the cavity as entirely part of the 'interior' environment, then it can be left unfilled, or ignored even if previous CWI is known to be a mess.