Efect on EPC rating of installing High Heat Retention Storage heaters in place of 'warm air electricaire' system.

[JohnW2]

So changing a say 20w CFL to a 100w tungsten will give you an additional 80 w of infrared heat. That would not be noticeable in a typical room requiring 1 kW. P

Quite - and 1 kW would be either a pretty small room or a very well insulated house (and probably violating the 'ventilation recommendations' )

 

[ericmark]

My oil filled radiator at 850 watt will maintain the main living room temperature should we have a problem with the boiler, it would take a silly time to get there if room allowed to cool, but it would maintain the heat. And this is with no other heating. I am looking for inferred output to make a room at 18ºC air temperature feel like 20ºC, and my living room uses 8 x 6 watt LED bulbs, and 3 x 20 watt strip lights which are not normally at full output, they light a display cabinet which adds to lighting in the room, so would say around 60 watt of LED lighting, that is if tungsten around 15 lumen per watt, and LED around 85 lumen per watt then would need 340 watt of tungsten light to equal what I had today, or the government has been issuing wrong figures. Likely actually would need 180 watt as I think we got more than 15 lumen per watt, so around 3 x 60 watt bulbs, which may not have given enough inferred to reach the feel like 20ºC may have needed to set air temperature up to 19ºC but the point is air changes don't loose that heat, it warms furniture and people, but not the air, so is more efficient as less losses.

I know with the last house in the days of tungsten the living room thermostat was set to 18ºC all day, from 7 am to 10:30 pm and a simple time clock in the garage with the boiler turned off the heating at night, but when we went to CFL I found in the evening when we were just sitting down, 18ºC was too cool, and I had to swap the basic thermostat for a programmable thermostat, and get rid of the time clock, so the air temperature rose to 20ºC in the evening, this resulted in the bedrooms getting too warm, so then I had to fit TRV's to bedroom radiators to stop bedrooms overheating.

Not saying this was a bad thing, but it did mean moving from tungsten to CFL was a lot more expensive than the government made out. Since heating my home with gas, using the CFL did save money, not convinced it would have done if I was using electric to heat the home.

Also the bulb sizes did not equate to what we were told.
As new build 2 x 100 watt, this was changed to 6 x 40 watt to get better spread, with two chandeliers, some times we did use 60 watt bulbs, would buy assorted packs, but on going to CFL we used 6 x 11 watt which looked rotten as too tall for the design of the chandeliers, so swapped to 10 x 8 watt Philips golf bulbs with a new chandeliers these were really far too dim, but we had paid so much for the bulbs, and told would last years, two rooms so 16 bulbs in all, within a year 6 had failed, and we had used cheaper larger bulbs in one room. as the continued to fail, replaced with 3 watt candle LED, which to start with looked better, but found room looked bright, likely colour temperature, but could not read a book in that light, so mother had a smaller room so used 3 watt in her house, and went to 5 watt in mine, so starting at 200 watt, and ended up at 50 watt, so if the LED is 85 lumen per watt, then tungsten was more like 20 lumen per watt.

The problem is tungsten was shining in all directions, LED is not, so the light reflects off walls and ceiling in a different way, so there was no direct comparison. And at the end of the day, in the days of tungsten I was renewing a bulb some where in the house once a fortnight, and today maybe one every 6 months, so all in all LED are better.

But I still do not see how they save energy, money yes as heat with oil now, but energy no.

So to heat a home with fan heaters is far more energy efficient than to heat with storage radiators as the fan heaters only heat the room when required, where the storage radiator can never switch fully off, but money wise then buy energy at night and using in the day with some thing like economy 7 will save money if the room is used 24/7. As what hourly usage the fan heater would become cheaper, would depend on air changes in the room, and the heat lost through fabric of the building.

However that was not the question, it seems the question is what the government approved software considers as the best option. And looking at homes and comparing it seems using storage radiators instead of gas with drop most homes from D to E band. Seems they are pushing heat pumps, but only electric, if you use a motor to transfer heat powered by 35 sec gas oil, the government has just changed the rules, and you have to use road taxes diesel instead.

 

[oldbutnotdead]

EPC is as observed a tickbox- there's no real inspection of the actual house.
I was expecting (and would have found the results quite useful) one of those infrared camera surveys- be handy to see hotspots on external walls or maybe in the roof.
But no- bloke with a clipboard.
He ticked no loft insulation until I dragged him into the loft and showed him there was 300mm of it (well I assumed from the age of the house...)

 

[bernardgreen]

an additional 80 w of infrared heat. That would not be noticeable in a typical room requiring 1 kW. P

A person in your typical room that requires 1 kW to heat it air volume would be warmed by the infra-red heat without the need to warm all the air the room

 

[JohnW2]

..... so would say around 60 watt of LED lighting, that is if tungsten around 15 lumen per watt, and LED around 85 lumen per watt then would need 340 watt of tungsten light to equal what I had today, or the government has been issuing wrong figures. Likely actually would need 180 watt as I think we got more than 15 lumen per watt, so around 3 x 60 watt bulbs, which may not have given enough inferred to reach the feel like 20ºC may have needed to set air temperature up to 19ºC .....

but the point is air changes don't loose that heat, it warms furniture and people, but not the air, so is more efficient as less losses.

You often say this, but I think it involves a considerable amount of over-simplification, in some cases to the extent of being essentially 'incorrect'.

I think that the main iffy assumption is that most (or, at least, a very substantial proportion) of heat coming from an incandescent bulb is transmitted by radiation (i.e. "IR"). As we've discussed before, ordinary glass is not very transparent to IR and, presumably at least partially because of that, the glass envelope gets very hot - so most of the transmission of that heat is likely to be by local conduction (to surrounding air) and convection (to all of the air in the room). I would therefore suspect that they radiate pretty little IR (instead, mainly heating the air) - which I think is consistent with the fact that if one puts one hand more than few inches from an incandescent bulb, one doesn't feel much radiated heat at all.

If that's the case, then 'air changes' do 'matter', just as they do with all other heating which is primarily by convection. It is true that, with such forms of heating, the fabric of the building, and things contained within in, eventually gets warmed by the heated air, and that one eventually ends up with a situation in which there is a lot more heat 'stored' in the fabric/contents of the building than in the air it contains - but if one keeps replacing the heated air with cold air, then I would think that the fabric of the building will lose its heat at much the same rate as it originally gained it.

... and, of course, as has been discussed, the contribution of heat (however transmitted) from incandescent bulbs would never be more than a fairly trivial proportion of the total amount needed to heat a room. It certainly would not seem to make any (financial) sense to revert (from LED) to incandescent lighting during the winter if one's primary heating was using an energy source which was cheaper than electricity.

Kind Regards, John

 

[ericmark]

I had not realised in 2018 the law had changed and the HHR was born. I had seen back in the 70's some really good systems using fans and a central heat store, and the guy I worked with said how as the weather warmed up he could switch off the charging power and a week latter with a cold snap there was still some retained heat in the system.

In around 2000 my brother-in-laws house was built, this used two very large tanks fitted with water, and lighting a fire in the evening would also heat the water and the water would maintain the house temperature once the fire had gone out, and the solar panels were enough to maintain the house at around 10°C to stop freezing with enough in reserve to reheat the house when the geofencing detected he was on his way home.

So we have had HHR for years, but the name is a new thing. Although it seems the law is 2018 I found

To qualify as high heat retention, products have to be tested and show 45% heat retention when tested in accordance with EN60531:2000 (as stated in SAP 2012 clause 9.2.8).

Clause 8.1 - Continuously charge in the minimum discharge condition in the test corner until the charging control switched off automatically for the first time. Energy consumption is stated as the continuous nominal charge. Charging time is the continuous charging period in hours and minutes.
Clause 10 - Repeat of clause 8.1 within the test calorimeter with the calorimeter ventilation rate set using the calibration curves. When the storage heater achieves the same value as that in the continuous charge acceptance test the charge is stopped and heater is switched to give minimum discharge. Heat loss is calculated using the pre-determined calibration curves, with the heater discharging for 16 hours.

So it seems to work out if the heater complies it must have some where EN60531:2000/A11:2019 on it? However it seems this was withdrawn on 17-Jun-2022 with Publication Date 17-Sep-2019 and of course we are no longer in the EU.

How an inspector works out if the storage heater is classed as HHR I really don't know, clearly they have been around some time, even if the law was only in 2018, and in 2000 I was actually involved with making the heat retention bricks, and was given a storage radiators to test the bricks with, it was a failure, the bricks are made with mainly iron, and traditionally this is bonded into a brick using clay mixed with the iron, to fire a kiln is expensive so idea was use concrete instead of clay, however when heated for the first time the iron changes state, and this releases water, so the bricks made with concrete still needed to be heated up so you don't get a pool of water under the radiator when first used, the energy needed to do this, tipped the balance and meant they were uneconomical to make this way.

But the radiators only had two simple controls, heat in and heat out, there was no automation, so I manually turned up heat output through the day, and then turned it down again before going home, the same applies to storage radiators as other central heating systems, to save money it needs to reduce the energy required, and with an annual bill of say £750 then to repay over 10 years you can't spend too much on the devices, and a HHR storage radiator costs around £750 and one is unlikely to recoup that expenditure, it would seem the way forward with electric heating is the heat pump.

The problem however is their size and the fact you need to distribute the heat around the house, and with storage radiators you have no existing pipework.

 

[ericmark]

... and, of course, as has been discussed, the contribution of heat (however transmitted) from incandescent bulbs would never be more than a fairly trivial proportion of the total amount needed to heat a room. It certainly would not seem to make any (financial) sense to revert (from LED) to incandescent lighting during the winter if one's primary heating was using an energy source which was cheaper than electricity.

Back in the late 60's the MANWEB building was built using fluorescent lighting to heat it, never mind tungsten not being enough, fluorescent it seems could produce enough?

However 2016 it was demolished.

 

[JohnW2]

Back in the late 60's the MANWEB building was built using fluorescent lighting to heat it, never mind tungsten not being enough, fluorescent it seems could produce enough?

Yes, I'm familiar with that, but the building in question was a very special case - with very high levels of insulation, reduced window area, heat storage facilities, and (presumably) very large amount of lighting and a very large number of 'occupants'.

In fact, it appears that 15% of the heat in the building came from the bodies of the occupants - which, strictly speaking, means that 'energy efficiency calculations' should take the food consumed by occupants into account.

Whilst it may have been very 'energy efficient', I doubt that it was particularly 'cost efficient', given that 85% of the heat (all but that from human bodies) was seemingly produced by electricity

However 2016 it was demolished.

I wonder why, if it was so 'energy efficient'?

Kind Regards, John

 

[ericmark]

I wonder why, if it was so 'energy efficient'?

I am told it got too hot, the building was full of windows

and they were a sun trap, but also MANWEB became Scottish Power so it was no longer run from Chester.

But I can't find the answer to how the ECP inspector knows if the storage radiator is HHR or not. Everything other than that is simple fitted or not fitted, they don't look at type of double glazed windows just if it has double glazing or not. I suspect another where it says "assumed" it seems rather than doing any tests, if not obvious, they just write "assumed"!

The only real way is to use a thermal camera, but that would mean it could only be done in winter with the heating on. Our building manager where I work tells me councils do exactly that, seems also the Police, but that is to do with farms in the loft. He has one which plugs into his phone, but not cheap, a few hundred pounds.

 

[JohnW2]

I am told it got too hot, the building was full of windows

That interesting - I must have misunderstood "... reduced window area (40% glass to wall ratio) ..." but, on reflection, it probably meant 'reduced' in comparison with other buildings designed to be heated primarily by 'daylight' (which apparently had a ~55% ratio).

But I can't find the answer to how the ECP inspector knows if the storage radiator is HHR or not.

Isn't that the same sort of question as "how the EICR inspector knows ..... "v- the answer being that he/she looks what's written on it (model number etc.) and then, if necessary, 'looks it up?

Kind Regards, John

 

[ericmark]

Isn't that the same sort of question as "how the EICR inspector knows ..... "v- the answer being that he/she looks what's written on it (model number etc.) and then, if necessary, 'looks it up?

Yes they can look it up, but HHR was around in the 70's, well before the EN number was invented, so looking it up would not really tell the inspector anything. Those council houses in Flintshire with the central heat store worked well, but well before internet, so how one would look it up don't know.

 

[Why Not Indeed]

ordinary glass is not very transparent to IR

Glass is transparent to IR - it has to be specifically designed to attenuate the transmission of IR wavelengths.

Measurement of Solar Transmittance through Plate Glass

Several types of glass were measured using a UV-3600 UV-VIS-NIR spectrophotometer and their solar transmittance was calculated using solar transmittance software

www.ssi.shimadzu.com

and, presumably at least partially because of that, the glass envelope gets very hot - so most of the transmission of that heat is likely to be by local conduction

The glass gets very hot. What do hot objects do? They radiate IR. So really, it doesn't matter if the glass blocks the IR, gets hot and then re-radiates some other IR, or just transmits the original IR. It's radiating IR in either case [as does anything warmer than 0°K].
It seems plausible to me that an incandescent bulb transmits more heat by IR radiation than convection and conduction. But I don't know how to verify this and it might be faulty reasoning.

 

[JohnW2]

Glass is transparent to IR - it has to be specifically designed to attenuate the transmission of IR wavelengths.

We went through all this quite recently. As I said at the time, it flies in the face of everything I have ever understood about "how/why greenhouses work".

I think that there is a lot of potential confusion due to the fact that the IR spectrum is very wide and that the transmission by all types of glass generally reduces with increasing wavelength. The graph in the link you provided (which is the first hit I get with Google) shows high transmission through "clear glass" over the whole region depicted, but that only goes up to 2,500 nm (i.e. 2.5 μm) - so primarily "NIR". There seems to be considerable variation in what people regard/describe as "thermal IR", but a fairly common view seems to be that 'thermal radiation' corresponds roughly to "MWIR", with a wavelength of about 4-8 μm (4,000 - 8,000 nm) If one takes that view, then the second hit I get on Google shows:

... which seems to show that transmission, for all the glasses considered, falls markedly as one moves through the MWIR region, done to almost zero by the time when gets to the top of that region. ... which might help to explain how/why greenhouses 'work'!

The glass gets very hot. What do hot objects do? They radiate IR. So really, it doesn't matter if the glass blocks the IR, gets hot and then re-radiates some other IR, or just transmits the original IR. It's radiating IR in either case [as does anything warmer than 0°K].

True, but when the hot objects are in contact with some material (including air) they transfer heat to that material by conduction (whence, if the 'material' is a gas or liquid, by convection).

It seems plausible to me that an incandescent bulb transmits more heat by IR radiation than convection and conduction. But I don't know how to verify this and it might be faulty reasoning.

As I said before, my suspicion, based on some theory and some 'experience', tends to be the opposite of that - namely a suspicion that only a small proportion of the heat transmission is by radiation. I've just repeated the 'experiment' I referred to - with my hand more than about 3-4 inches horizontally from a 100W incandescent, I struggle to convince myself that I can feel any heat,, but with my hand about 12 inches above it, it rapidly comes to feel quite warm. That seems to support my suspicion that most of the heat transmission is by (conduction-initiated) convection. I don't pretend that's any proof of anything, but it is certainly not inconsistent with my suspicions.

Kind Regards, John