The houses currently have solid concrete floors with no insulation underneath them. As a part of the retrofit we are excavating these original solid floors, and replacing them with a combination of insulation laid under a new concrete floor. Putting the insulation underneath allows the mass of the concrete to store heat and then give it back up as the air temperature in the house cools, thereby helping to keep the house warm.
Effectively the floor is then acting as a storage heater. The heat absorbed into the floor is from a combination of passive solar gain and incidental gains from occupants, cooking and appliance use. Basically whenever the air temperature in the house exceeds the temperature of the floor slab, the floor will absorb that excess heat. The insulation under the floor slab stops the heat escaping to the ground below, storing it to be returned to the house as the air temperature subsequently cools.
The existing solid walls will act as a heat store in a similar way once the new external wall is built up with the insulated cavity outside the existing wall.
The video below shows one of the houses with the old floor excavated and Nick summarises our plans for the new floor.
[youtube=http://www.youtube.com/watch?v=yjePXnOUgKM]
Its an Aero chocolate bar in reverse of course!
[youtube=http://www.youtube.com/watch?v=tqivPdW6fE4]
(not that we’re endorsing a Nestle product)
We’ve now removed the chimneys from both properties; there are two key reasons for this:
- They are no longer be required as the gas fires have been removed;
- They are a significant source of heat loss.
This also makes it easier to fully insulate the party wall between the properties; this has two benefits:
- It provides sound insulation between the properties;
- It prevents heat being lost from the properties by being transferred through the wall up into the loft space.
It is often wrongly assumed that you don’t need to worry about insulating party walls, since assuming your next door neighbour is heating their house, then there will be no heat loss. However, research has shown that heat will be transferred via the party wall up into the loft space and to the outside. Insulating the party wall on both sides will prevent this from happening.
So that just leaves the question how will santa gain access on Christmas Eve? Well, we’re guessing he’ll use the roof lights in the newly added sun space; its flat roof will be easier for him to park his sleigh on too …
[youtube=http://www.youtube.com/watch?v=pzAkUxNvKfM]
Today we received the thermal imaging photos that were taken of the houses before we started the retrofit work.
Thermal images are photos taken with a heat sensitive camera that shows the temperature of the subject. Photos were taken of the houses before we commenced the retrofit work to illustrate the areas of heat loss from the building.
Similar photos will be taken after we have completed the retrofit work, and will hopefully tell a very different story.
The photo below illustrates the high level of heat loss from the bay of number 28 – the lighter the colour, the higher the temperature, and hence level of heat loss from that part of the building.
If you are surprised by the level of heat loss from the bay, the video below will show you the reason why.
[youtube=http://www.youtube.com/watch?v=JFiC9o6RvwY]
Don’t be misled by the light colour of the roof; the loft space was quite well insulated, and we believe this high temperature was caused by direct sunlight falling on the roof. Additionally of course, it could have been caused by heat escaping up from the bay, as we saw in the video above.
The bays are being removed as a part of the retrofit, so will no longer be an area for concern.
In the video below, project manager Nick Martin talks us through the main fabric improvements that are going to be made to the properties.
Our aim is to incorporate HHP design principles in a retrofit, i.e. combining high thermal mass, passive solar gains and high levels of insulation to remove the need for a space heating system, and therefore significantly reduce running costs and emissions from the homes.
[youtube=http://www.youtube.com/watch?v=gI7tFBMrHfI]
We will post further videos over the coming weeks looking at various aspects in more detail as we progress the retrofit work. We hope you enjoy this summary, and please let us know what you think.
