I've been looking at a few new build (or second hand, less than 3 years old) apartments for purchase as an OO.
There is no gas in the properties and electric panel heaters have been installed in all rooms.
Does anyone know how much one of these costs to run in a year given the current insulation requirements? I'd be working from home so I'd need the living areas to be heated all day. Normally, I would accept the inconvenience of a Storage radiator for this but as the meter is down in a dungeon somewhere, installing a circuit for this is likely to be next to impossible? (Unless anyone knows different)
(For clarity, I don't need a discussion on the unit costs, I'm thinking "how much of each day will the heater need to be on, given a certain outside temp")
Ask the builders/architects for the heat loss calculations? If they don't have 'em (which the should) how about the local planning department.
That would give you an idea of the insulation levels thst (should!) have been incorporated into the construction, after that it's number cruching time.
You can calculate the heat losses if you can guess area of windows, wall, floor/ceiling.
Outside Temps:
+3oC to -2oC over 24hrs, icy 10mph wind.
Modern room:
5x3m room, mid-flat re heat above & below, single outside wall of
3x2.5m, glazing of 1.8x1.2m, double glazed, no open chimney. Heated to
21.2oC. About 380W per hour average over 24hrs.
1950s room:
5x3m room, solid uninsulated concrete floor, single outside wall of
3x2.5m, glazing of 1.8x1.2m, single glazed, uninsulated roof of 1x3m, open class-1 chimney with turned off gas fire in hole. Heated to
21.7oC. Measured 1120W per hour average over 24hrs. Ok, the chimney was still a bit warm from previous days so would draw heat out.
Sunday had a gas outage so could directly compare 2005 v 1950 build. Comfort wise the gas radiant means a 19.7oC room temperature felt far warmer than 21.7oC created by a fan heater cycling.
I would replace the panel heaters by Dimplex Duoheat of an appropriate size (you need to do the calculations, then verify them with inside/ outside thermometer and an energy meter on the heater - wind is less of an issue compared to an open cavity with numerous vents, inevitably leaky single glazing, open chimney).
To get E7...
- You simply ask the supplier for E7 metering.
- You use local timers on each storage heater.
For E7+Peak storage heaters like Duoheat you basically connect both to the existing cable, but with a timer on the E7 part. That is assuming the existing cable can handle the draw. Duoheat have lower NSH draw than conventional heaters - basically 0.85kW, 1.7kW, 2.55kW which is
3.5A 7A 10.5A roughly. Your existing panel heaters will be 2A minimum (500W), quite possibly 3A (750W) so you can probably run a Duo400i. I doubt you will need Duo500i on a modern insulated house.
Insulation makes E7 work, basically like a GCH radiator that never switches off - you size so you do not fry overnight, but so the peak element comes in from 2pm onwards. Peak rate panel heaters are aimed at out-all-day people and just background trickle until people get home. The insulation is probably on the inside so very rapid warmup rather than trying to keep a brick building thermal store charged like a storage heater - brick outer skin, woodframe stuffed with insulation inner?
Alternatively you may find the panel heaters are ok - realise E7 means peak-rate is higher cost (25% higher roughly).
Are you saying that you need to put in 380 W of heat each hour to keep the temperature constant after you have reached working temp?
So that's (approx) 5p per hour = 5 * 24 * (say) 150 days = 180 pounds per room. Times three rooms = 540 pounds for annual space heating.
Does that seem reasonable? (As in "the calculation"!)
In my current, badly insulated, (rental) apartment I have used (approx) 3000 kW (of gas) in the 75 days over this winter, so that's 1500W per hour for the whole house (including water heating), so that's a bit less that your figure. Though I need the heating on for over 200 days here.
This is the issue. If the cabling isn't suitable, then one is stuffed!
I doubt I'd need a 400, the rooms are tiny :-( I only want to heat up the living area. I like the bedrooms to be cold(ish).
It might already have something like this, but I doubt it. It doesn't look like the picture and they aren't floor standing.
380W/hr average over 24hrs includes raising it from 15.2oC to 21.2oC.
Peak rate on E7 is say 12p/hr, Night rate on E7 is 5p/hr.
For a flat the figures would probably be...
- Peak rate panel heaters - =A3350-520 with very recent insulation.
- E7 rate storage heaters - =A3120-220 with very recent insulation.
Can you remove a wiring accessory or CU cover?
- Are the heaters wired on individual radials or on one radial (20A)?
- Is the cable 1.5mm to each heater or 2.5mm?
From what I have heard...
- Living area on Duoheat
- Bedroom area on Panel Heaters
I have also heard of people removing the Duo300i from bedrooms as too hot, which considering they are just a 0.85kW x7hr storage heater means the insulation levels "must work very well". You might want to change a large bedroom to Duoheat 300i or at least budget for it (order it in the middle of the next winter when the couriers can't make it :-) A Duoheat 300i is 3.5A E7, 1A Peak which should not stress anything.
Only other note is storage heaters are heavy. Guessing about 47kg - 87kg - 110kg for Duo300i 400i 500i. So if you are attaching to plasterboard, find the studs.
A flat with tiny rooms may well have minimal heating requirements - recent insulation levels are huge, something like 0.16U for the roof,
0.35U for the walls, mid-floor flat has heating above & below, windows are often tiny on modern build. So I suspect a single Duo500i in the living area may do fine, you will have to do the heating calculations. That is not too onerous since you can come up with worst/likely/best case scenarios to give a range.
Insulation makes E7 work - well. They are just a hot lump which doesn't hot/cold/hot/cold like GCH. Whereas with uninsulated houses & undersized E7 heaters they are a pig because they just run out.
Many flats skimp on heating a) Electric boiler a) on peak (!) not E7/E10 and b) no thermal store (!) b) Panel heaters throughout which has no thermal mass compared to NSH and run on peakrate.
The former is not uncommon, but the latter is popular with builders as it can save a lot - buy a handful of heaters for peanuts compared to what are expensive Duoheat. Recently I u/g my mother's to twin Automatic NSH rather than Duoheat because of space and for reliability. Having twin E7 NSH is good because if one fails you still have another AND you can service one (they take a while to cool down). That is just to heat a hallway, nothing beats true radiant in living areas - one reason why gas-fires still cling on despite the draughts & inefficiency and why wood burners have become popular.
Aside - anyone finding a gas fire causes a draughty room, check the closure plate tape has not pulled away behind it otherwise not only do you risk spillage with a cold chimney but it will create a huge howling gale if your chimney draw is high (I estimate about 20% gas usage increase to compensate).
#1 - You can match gas by application of insulation :-) This is particularly true on the most expensive to heat rooms such as living area because heat loss increases with desired room temperature (delta over outside).
#2 - Oil price comparison needs care due to lag. Oil is often a spot-price whereas gas/electricity can have quite substantial lag - we are due a 15-25% price rise soon.
#3 - Realise gas price excludes maintenance Annual maintenance contracts in particular can really hurt economics vs "capped-bill-when-needed", replacement depreciation can equally be ugly and no easy solution there. So gas is not quite as economic as the bare figures suggest, an automatic (capillary) E7 heater will last
25yrs+ until you are so fed up with the ugly thing you'll shoot it.
Obviously oil is nasty in that it has all the maintenance & depreciation costs of gas (if not slightly more) - plus the higher cost of oil which seems timed to not be cheapest when you want it re one-off bulk purchase (spot price).
#4 - You can negate some of the gas/electricity price variations by owning a good energy fund, takes quite a few =A3k though and is not likely to deliver the easy returns of the past unless we return to
12$PB. Better long term funds are aimed at 3-4%-over-CPI which have limited return but also limited drawdown even in the past crisis. For example Caznove Multi-Manager Diversity Income returned about 80% of a good equity fund trough-to-peak but in the crash only suffered about 25-33% of the equity-funds peak-to-trough. They use hedge-fund instruments & multiple asset classes, but are highly dependent on the manager - although returns aim to be "very modest indeed". There are other fund managers offering similar.
Using insulation & trading energy funds I have reduced my mother's heating cost to pre 2004 levels despite 2009 winter & the house about
1.5oC hotter overall (that would normally require about 15% more energy). Intention in the coming months is boost insulation, a pilot of Tredaire Dreamwalk v Rubber-Crumb or 3 v 1 Tog shows even that makes a very noticeable difference. That nagging calf pain is gone. Same goes for window film or secondary glazing since DG is mostly "when structurally required" since it has miserable economics re payback period.
Truly recent insulation of 2009 figures could be very good. What matters is HOW the insulation is done - inside insulation means no thermal mass, but very fast warmup so on-demand heating can work well since it only has to heat a body of air (fast). Conversely insulation on the outside of a house means enormous thermal mass, which requires long term background thermal input to "charge it" and would perform miserably if you tried an on-demand heating approach (walls would remain icy).
If so, one person (100W or so) sitting at a computer will more less provide this.
When I was selling my SuperHeat program the SAP analysis on flats built to current building regs often showed that the DHW energy cost was more than the space heating cost.
I wonder if anyone followed up on the design calculations to see if it reality matched the theory? No reflection on SuperHeat intended, I can see a sloppy build blowing the theoretical losses in short order or an uninformed occupier incurring extra expenses through misuse of the heating system.
That is the problem, she is - at least until it hits about -3oC or foggy. Mar-Nov and every window/door will be off never mind open. Beds open, windows open :-)
Living room may be 20.5oC, but bedrooms are a "mandatory no heat" which meant they used to dip down to 12.1-13.2oC for several hours which is too cold. Now due to insulation plus a small automatic heater elsewhere they now hold 14oC even on the coldest -9oC 7pm & -19oC 6am recently, otherwise dip to 15.2oC. Target is 16oC for bedrooms.
This year will see an unheated (unheatable) box-room which got below
-1oC on the -19oC night superinsulated so permitting viable background heating to about 14oC. Two outside walls, one being solid, plus a large open underfloor porch with poorly fitting ceiling means it gets cold in the prevailing wind. Superinsulation will get heat loss down from 790W to 250W. Useful because it is the neighbouring room and effectively makes her bedroom interior wall an exterior wall re temperature. That is below =A360 for a 100-day winter compared to what would be over =A3180 if it were heated currently.
Then it is dredge out a cavity wall which has two spots of rubble about 18in above floor level, soil pipe, old gas wall heater, other holes so it can get polybead cavity wall insulation. Removing plaster to insulate the larder confirmed a wet arch exactly where I suspected it was and a test core drill confirmed "rattly loose rubbish". Rarely heated rooms and a "corridor room" which is electrically heated will get superinsulated on the inside down so their baseline temperature is either higher or significantly cheaper.
UK should have insulated better much sooner really, Germany is at 8" Kingspan which is a bit ridiculous (10mm PIR halves heat loss on a solid double brick wall, 200mm is far into law of diminishing returns although the Greens believe otherwise). Insulation has a good payback when she isn't paying for it :-)
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