Insulate better than I said and you could end up with not needing a formal heating system! or heating bills, maintenance or installation costs either -- appealing?

As if by magic!

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=998&page=1#Item_0

Hi Jeff,

We are currently looking at something very similar about 100m2, along with extra insulation all round and draft proofing, the plan is: pull up existing floor boards, insulate below and between suspended floor joists, fit wet UFH, dry limecrete over pipes to top of joist, refit floor boards, sand and seal. DHW and UFH via thermal store run off Calimax Twist 80/20 pellet stove (10Kw) in kitchen breakfast room and solar on south facing roof, supplemented by small wood-warm stove (3Kw) in living room. Along with energy saving lights (Megaman) throughout we reckon to reduce bills by 2/3 to 3/4 compared to existing night storage and immersion. CO2 down by 80% to 90% (depending on your point of view re pellets) The UFH is offset by not needing carpets.

richard

See Jeff's other thread: http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=999&page=1#Item_0

Which ever way you look at it I think 'extensive rebuilding' just about covers it!


S.

Cheers, especially for the links.

I don't want to divert the thread from heating/insulation but - as for light bulb heating, I am not a fan of the energy efficient bulbs which give off less heat. Those I have seen so far take too long to brighten up and from what I can gather need to be left on to be efficient due to the high start up load. If traditional lights are switched off when not in use I understand the energy used is comparable.

I put a heat recovery system in my last house. Used 2" polystyrene insulation in all floors & walls & heated with a conventional oil fired combi. The roof had Tri Iso foil insulation (heavily overlapped and taped joints, counter battened & Tyvek breathable felt under tiles. The extensions were built of: overlapped clinker style wood cladding to mimic the lean to barns they replaced; vapour barrier (Tyvek); 35mm battens giving another air gap; 9" Celcon thermal blocks (GLUED, not cemented); air gap; 2" polystyrene insulation; finished off with 12.5mm plasterboard & skim. Bills quite reasonable - had a 1200 ltr oil tank which was topped up twice a year (+electricity for the recovery system). Didn't seem excessive for an 1800sq ft exposed barn which took a lot of wind and which started out as a 9" solid brick wall construction with no roof & an earth floor.

But I was not thinking about not having a heating system at the time - yes it is a different mind set.

If I go for a heat recovery system again and upgrade my insulation and windows I would like to think I could get away with a stove & nothing else for heating. But even given extensive rebuilding I am still dealing with and existing structure and will have to work within these confines. How do you move heat around the house? Via the recovery ducting or a separate system venting it into remoter areas of the property before recovery & redistribution?

I'll play with the links you have given me. Thanks for info so far - great forum & a lot of knowledge here.

Posted By: richardab1967I do believe that SAP is not very accurate when you get down to seriously low energy houses, but it is a useful exercise to do as I input my existing house and it approximately got the energy use about right coming up with space heating of 19000kwh/yr for a 125m2 house (2005=20200kwh, 2006=19700kwh, 2007=14900kwh). Actually these are average to below average figures compared with the national average I believe.

Given the climate you're in, those are pretty poor figures to be honest. I live in a much harsher climate - daytime "high" temperatures the past few days have been around -12 to -14C with nighttime lows in the -20s. We have a 185m^2 house and the annual energy consumption for everything (heat, light, hot water, appliances etc.) comes in at about 22,000kWh/year. Our calculated heatload at an outdoor temperature of -23C is 15.7kW so I'm amazed that you would need 10+3kW of heating capacity for a climate with a design temperature of probably closer to -3.5C. Our load at that temperature is 8.3kW. We're still a long way from not needing a heating system, but our figures are a lot better than yours seem to be - and this is a 109 year old house with no insulation in the walls, solid brick/stone and an uninsulated basement floor. We did a lot of work on air tightness though.

Paul in Montreal.

Jeff

'I don't want to divert the thread from heating/insulation'

Threads on here go all over the place (sometimes very strange places) but usually someone pulls it back at somepoint.

For multifoils - have a look at the epic thread I dare not comment.

As for moving the heat around, I am no expert but think it all depends on what you design. The suggestion seems to be that passive stack is less controllable and not as good as redistribution via MVHR (you can be sure someone somewhere thinks differently). Hopefully the links will help.

When the boys settle they'll start helping too I'm sure though you are more likely to be sent down the 2 foot of insulation route here.

S.

Hi Skywalker,

"For multifoils - have a look at the epic thread I dare not comment".

I have read some of the multifoil thread. I have used it on x3 barn conversions now & lived in one of them for 4 years. I did not add any additional insulation to the roof voids. It is interesting watching that discussion going backwards & forwards. For what it is worth I think it does work but if I had insulated even further I would have had lower bills. Do I think it should be supplimented - yes. I do not think in the real world and given the values we would all like to achieve today that it is sufficient on its own. I have no figures to back this up - just a feeling from having 'lived with it'.

Richard

"I have read the arguments about solid ground floors ...."

Another thought I had was the use of a ASHP linked to an underfloor wet system which together with the stove should cover heating nicely. I do not need to change the existing floor slab. I have enough head room to simply retrofit/install the system on top and tile/laminate/carpet as desired (I know it is not so simple but you get the idea). I do not think solar will work in my location. South is behind me and upslope so I think it unlikely the gain will be sufficient to warrant the cost. Payback will be too long. Once again - no figures - just gut feeling.

As for hot water - a backboiler for the stove and an immersion heater should do it. Any other options?

And above all - good insulation & draft proofing. Time to start crunching numbers I think.

If you are going for ASHP/stove/UFH presumably you need a heat store (big very well insulated cylinder with a heat exchanger for DHW) to run it all from.

I'd do the figures on solar (unless you mean UPslope!) as you may still get good summer performance and you can get good quality DIY systems now. I do not know anything about ASHP in terms of their response time etc and how much they cost to buy/operate but I suppose this may make the solar redundant in any case - intersted to know more.

Other than that let us know which way you jump & how well it all performs.

S.

Richardab1967 - like you I too am always interested in comparing other folks heating requirements to ours! I have some figures as below. But first, can anyone tell me please, am I correct in taking it that burning one litre of heating oil produces about 10.5 KW of heat (assuming 100% efficiency)? If so, if I am using 3000 litres of oil p.a., our boiler must be producing about 24,000 KW p.a. (assuming 75% efficiency, as we currently have a 10 year non-condensing boiler). If so, I am ashamedly well above the UK average quoted above (17,700)!

However we only moved into this place fairly recently and are undergoing a significant insulation/draughtproofing campaign prior to a complete revamp of the heating system, so it will be interesting to see the difference. Incidentally the total floor area of our place (dormer bungalow in an exposed, slightly elevated, windy location in west Wales) is about 180 sq.meters. This means I am a million miles off the Passivhaus figure of 15 x 180 KWh or 2700 KWh p.a. and still would be even if I reduced our oil consumption by two-thirds! Nevertheless we will press on and do what we can.

http://www.sustainable-energy.vic.gov.au/ftp/advice/business/egmtoolkit/Module3_Appendix3.pdf
says that Heating oil and Light Keroseen are similar and contain around 36 GJ/kl (36 Giga Joules per thousand liters).

So if you burn 3000 L per year that's about 108 GJ per year. (= 108 x 10^9 J)

There are approx 31536000 seconds in a year so if the boiler is on 24/7 that would be

108 x 10^9 / 31.5 x 10^6 = 3.428 x 10^3 Watts

or 3.4KW

Most likely you boiler isn't on 24/7. What percentage of time is the boiler actually burning?

50% = 6.8 KW
25% = 13.6 KW
10% = 34 KW

CWatters - many thanks for taking the time to do the calculation.

I can't really say how long the boiler is on. Currently the time switch is set for 2 hours in the morning and 6 hours in the evening i.e. 8 hours per day but obviously the boiler is not alight for the entire 8 hours. What would be a reasonable estimate - about 50% of the time say? (4 hours per day) = 16% = approx. 20KW from your calculation.

The specification for the boiler indicates that it can burn about 3 litres of oil per hour. If kerosene produces 10.7 kWh per litre, then the boiler should produce 32 kW per hour. Assuming 80% efficiency, then this becomes 25 kW per hour which is the stated output for the Heatslave boiler I have. How do I relate this to the figure of 20 kW calculated above?

Ted - thank you for providing the heat content of kerosene data. I tried the link you gave but I cannot download the information without registering with the Carbon Trust first it seems. Can I register as an individual, as the site seems to be set up to deal with organisations only?

Paul in Montreal - thanks for your helpful comments. I think you meant to add that at 60 mph it would take 1 hour to cover the same distance, but I know what you meant. Things are beginning to fall into place now! Working backwards: my boiler last year consumed about 3000 litres of oil. As it is set to burn 3 litres of oil per hour (and I assume this is a fixed rate for my particular boiler unlike the car analogy? ) then the burner was operating for 1000 hours. The heating last year was on from October to March i.e. 6 months, or 180 days. If all the oil was used just in those 180 days then that would equate to 1000/180 = 5.6 hours firing per day. Clearly it is not that simplistic as the oil is also burnt to provide hot water EVERY day of the year, so the figure of 4 hours burn per day during the colder months for space heating purposes looks reasonably accurate!

The bottom line is we are using far too much energy to heat this house and it will be interesting to review the situation after all the insulation work is completed.

Tony - yes, sorry I should have added that. Definitely not forgotten though!

Jeff B.

jeff - I would be interesting to know your floor area in square meters for both floors. I'm burning much more oil than the above gold standard as well.

Just to answer your questions...

<blockquote><cite>Posted By: Jeff B</cite>CWatters - many thanks for taking the time to do the calculation.

I can't really say how long the boiler is on. Currently the time switch is set for 2 hours in the morning and 6 hours in the evening i.e. 8 hours per day but obviously the boiler is not alight for the entire 8 hours. What would be a reasonable estimate - about 50% of the time say? (4 hours per day) = 16% = approx. 20KW from your calculation. </blockquote>

Almost impossible to estimate the percentage on/off. Most oil boilers burn close to their rated power so..

<blockquote>The specification for the boiler indicates that it can burn about 3 litres of oil per hour. If kerosene produces 10.7 kWh per litre, then the boiler should produce 32 kW per hour. Assuming 80% efficiency, then this becomes 25 kW per hour which is the stated output for the Heatslave boiler I have. How do I relate this to the figure of 20 kW calculated above? </blockquote>

...20 KW or 25 kW is about as accurate as you can get without using some kind of data logger to record the actual burn time over a year.