Insulation

[rct]

Hi All

Please can you help. We moved into a detached house a year ago, it was built in the 1980's and we find it very cold.
It already has cavity wall insulation when it was built and we have added 200mm of loft insulation to the excisting 100mm. It has had new door and windows and the boiler has just been replaced.
The problem is the house becomes cold very quickly once the heating goes off, even on mild days where the outside temperature is 13-15°C and the house has been heated to 20°C within a couple of hours the inside temperature has droped to 16-17°C. On colder days last year the radiators had to be very hot all the time to maintain the indoor temperature.
The energy performance of the house was rated at a potential of 67%. Is there anything else we can do to improve the insulation in the house. At the moment we are wishing we had gone for a new build just for the fact it would be warmer and cheaper to heat.
Thanks

 

[stuart45]

What was the actual, not potential rating of the EPC? What did it recommend? A detached house loses more than a semi or terraced.

 

[rct]

The actual was 62, most improvments ie new boiler, windows, cavity wall insulation was already done. It just recomended better loft insulation and energy saving lighting.

 

[brig001]

A lot depends on the construction of the house, but generally:

Air passing between ground floor ceiling and first floor boards. This can be sealed by lifting the floor and sealing joists and pipes where they penetrate the inner leaf of the wall.

Air leaking from integral garage. This can be round pipes, cables. gap round ceiling edge etc. and can be sealed from the garage.

Air leaking round pipework and cables. Seal these from inside. Look for telephone, TV aerial, satellite cable, outside tap, toilet overflow, drains, soil pipes etc.

If you have suspended timber floors downstairs, seal skirting boards to floor and seal around radiator pipes.

If you have plasterboarded walls, from the loft, seal to top edges of these to the wall. Draughts can get behind plasterboard and come out all over the place - so this isn't easy to fix.

It isn't easy, I have nearly finished my house and it's only been a year... It is worth it though - our house is much warmer now.

HTH,
Bri.

 

[^woody^]

Is the house timber framed?

 

[JohnD]

where the outside temperature is 13-15°C and the house has been heated to 20°C within a couple of hours the inside temperature has droped to 16-17°C.

nothing unusual about that

On colder days last year the radiators had to be very hot all the time to maintain the indoor temperature.

Tell us the sizes of the room and the sizes of the radiators please.



is the house damp, do you get condensation?

how much gas do you use per day (averaged over a week or so)?

Do you leave the internal doors open, or, is it open plan?

Do you have suspended timber floors over a void? Do you have carpets or what?

Can you detect draughts around doors, windows or fireplaces?

Does the loft hatch fit well, and, if you go into the loft on a cold night and close the hatch, can you detect warm air going up into it, e.g. round holes for pipework?

 

[rct]

Thanks for your replies.

I hope the following info answer some of your questions.

The house is brick-cavity-breezeblock with solid concrete floors downstairs and timber/plasterboard partitions between rooms.

The house seems well draft proofed and has no fireplace/chimney. The loft hatch is a good fit and is draft proofed, all pipes in the loft are lagged and holes around them are filled with insulation.

We get through about 4-5 units of gas a day for heating and hot water. The heating is on for 2.5h in the morning and 4h in the evening and use a 100lL tank of hot water per day.

The house has a small hall 4x8ft with a single convector rad 1000x600mm and has the stairs to the upper floor and a wc off to the side.
The hall opens onto a lounge/dinner, lounge part 16x10ft and dinning room 8X10ft. The room is north/south facing, 6ft French doors to the south side and a 6x4ft window to the north. There are 2 double convector rads, one at each end of the room 1000x500 & 800x500mm. The heating stat is in this room.

Accessed off of the dinning room is the kitchen and utility room. The door to this is always left open but we keep the door to the hall/lounge shut as much as possible.

The walls to the house are not damp, just cold. We do get condensation on the upstairs windows on cold nights and sometimes downstairs.

I hope this helps

 

[JohnD]

That usage does seem rather high. I have a comparable home, my usage is about 0.6 cu m/day summer, 2.5m/day Autumn, 6.5m/day winter, 1170m/year total. As I live in the Sunny South I get a lot of solar gain though during the day.

This is down from 1560m/year before I had my very old boiler changed and replaced the worn-out TRVs.

You would save a bit from fitting TRVs to all the rads except one of those in the room with the wall stat, but not so much that it would repay the cost of paying a professional to fit them for you. But it is a worthwhile DIY job. If your boiler is very old and inefficient a new one might save you 10% p.a (my boiler change saved more than usual). Have a look at the pipes between the boiler and the hot water cylinder, they should be lagged heavily in Climaflex or similar (if the pipes are long and uninsulated they can waste a lot) as should all pipes in unheated areas like lofts or garage. Look to see if the cylinder has a sprayed foam coating, and/or has one or two red fibreglass jackets round it.

I take it you do not have a gas fire.

Have a look to see if the flow from boiler to cylinder is pumped or gravity (look for a motorised valve like

and if the cylinder has a thermostat strapped to it like

if not, your HW is inefficient and wasteful

Use a thermometer to find out the temperatures of the rooms after the heating has been on for a couple of hours, and the temperature of the hot water from the taps. This may give some clues. BTW 100 litres is about one hot bath. Many people use twice this in a day if they wash up individual mugs under the running hot tap.

Feel the Flow and the Return pipes on each rad to see how hot they are. the flow pipe should be about 60-70C (this is "too hot to hold") and the return pipe should be about 20C lower (this is "too hot to hold for long")

Tell us the make and model of your boiler. If it has not been serviced recently it might be running inefficiently. For a few days, take frequent meter readings and see (1) if the meter moved when the heating is off (2) how much is moves per minute when the heating is running (3) how much it moves in 24 hours on a cold day and on a mild day.

Thick lined curtains, especially on large windows and your french doors, will help a lot.

Are any of the rooms open to the hall or stairway?

I am a householder not a pro.

 

[brig001]

where the outside temperature is 13-15°C and the house has been heated to 20°C within a couple of hours the inside temperature has droped to 16-17°C.

nothing unusual about that

Sorry JohnD, but that does sound unusual to me. To drop that quickly with well insulated brick/block construction (high thermal mass) is just wrong. I would bet that the outside walls are plasterboarded and the heat is escaping behind them.

OP, are these walls plasterboarded?

Bri.

 

[alittlerespect]

Probable causes 3 in No.

1. The central heating system is undersized (probability = likely)

2. The ground floor is uninsulated (probability - highly likely)

3. The construction detail for the internal face of the external walls is not as anticipated that is poorer quality blockwork has been used than anticipated - leading to higher heat losses (probability - maybe).

Solutions

1. Get someone to size up the central heating system (try the plumbing section - maybe there's someone who can assist - if not find a plumbing company and ask how much to do the calcs and provide a quotation to carry out recommendations.

2. Create a floating floor on the ground floor - may require heightening the door frame to accommodate the raised floor height. Use 50mm PIR insulation and t&g chipboard (all tongues glued with PVA adhesive) or use engineered floor to finish.

3. Determine the construction detail - drill a 50mm core hole in an inconspicuous spot - behind the sink cupboard or behind the bath panel. Take sample of blockwork and insulation material in cavity - fill hole with crazy foam and tidy up. Then take a closer look at the samples and try and indentify the material so that the U value of the wall can be determined with some accuracy. U value for 1980's building with retrofitted cavity wall insulation should be around 0.55W/m2K - an uninsulated wall would give you around 1.3W/m2K.

In energy terms assuming winter conditions and heating on for 10 hours and a temperature differential of 15C the heat loss for an uninsulated building would be :1.3W/m2K x 10hrs x 15degC = 195W/m2

for insulated wall: .55W/m2K x 10hrs x 15 deg C = 82.5W/m2

% saving 82.5/195 x 100 = 42% saving in energy consumption.
for insulated wall .

Regards

 

[rct]

Thanks

The ground floor is uninsulated.

When we had the boiler serviced the plumber did say the boiler is on the edge of being to small for the property.

We have drilled holes through the walls in different places for extractor fans, venting cooker hood ect. The only problem I have found is offten there is very little or no insulation present. I dont know what is usual for wall insulation, the stuff we have is like yellow loft insulation and is in small fluffy balls.

Can the insulation be topped up or replaced?

I think the only other solution maybe to add insulated plasterboard onto the inner wall. I dont want to do this because of the cost, disruption and it would make the living space even more narrow.

 

[JohnD]

the cavity insulation you describe sounds like blown fibre. It is the sort usually put in to older houses long after they have been built. You may even be able to detect mortar-filled holes in the walls where it was put in. The stuff fitted during build is mostly a rigid insulating foam, which is put in as slabs before the second leaf of brick or block is built (sometimes a mineral wool bat is used). I understand the foam slabs are better insulators than the fibre.

the blown fibre can be effective, but the whole cavity should be loosely filled with it. It sounds to me like yours was maybe put in badly, or might have settled in the wall after build. I don't know how often that happens because you don't see it until you demolish a wall. I have heard that if mice can get into the cavity they make nests and tunnels in it but I don't know how reliable that is.

I have the blown fibre, and where I have made holes I have been quite happy with it. You do have to pack fibreglass loft quilt or similar into the cavity when you make a big hole though to stop it falling out or being dislodged, e.g. if you are fitting an extractor duct or a wall safe.

Good cavity insulation makes a tremendous difference, so I think you might do well to start a new thread about that as I don't know what can be done about it.

 

[alittlerespect]

Hi I've done some calc's and research on the U values and heat loss for your property and have come up with the following figures:

Floor U=1.47 (ignore any lesser figures as they will relate to an extremely larger footprint building. Smaller the footprint of the building the greater the heat loss
) - Heat loss in 1 hour = 31W/m2;

Walls U = 0.87 (I have not include wall insulation as from your description its not providing much contribution - previous figure was taken from a table - this is the U value for your wall construction) - Heat Loss in 1 hour = 18W/m2;

Glazing: U = 2.8 (Standard Double Glazed Units) - Heat Loss in 1 hour = 59W/m2 - assumed glazing and external doors take up no more than 15% of wall space;

Roof: U = 0.14 - Heat Loss in 1 hour = 3W/m2

If you want to improve your wall insulation Gyproc do a 50mm thickness board 'thermaline super' which you could basically stick on the wall and this would reduce your U value to 0.34 W/m2K Reduced heat loss around 7.5W/m2

Floor put down 50mm PIR insulation board top with vapour check and finish with timber as previous this would reduce the U value to around 0.44W/m2K and would result in a reduced heat loss of around 9W/m2.


Final option to consider is alternative energy solutions e.g. sustainable and renewables to reduce energy consumption and the carbon footprint.

Regards