Thursday, 23 January 2014

The wind whistles through

If you look up draughtproofing you will find lots of standard advice about putting insulation strips around the joints of windows and doors. But how do you know where the real draughts are coming from?

Energy saving no.5: Use smoke to detect draughts
For this you need incense sticks, which you can get from the type of shop that sells scented candles. This was such a dangerous shopping trip for me, because I had to wander round several shops full of fancy cushions, ornaments, co-ordinated kitchen accessories and other cute appealing 'stuff', some of which were still reduced from the January sales! I was incredibly restrained to only come home with the incense...... er.... and a throw from a charity shop (which really was an impulse buy because it matches nothing, but at least it was secondhand and will go straight back to the charity shop!) I finally found the incense in Wilkos at £1 for 20 sticks.

The theory goes that you can use the smoke from the incense to show where draughts are coming in. Start by making sure all the windows and any vents are closed. Then turn extractor fans in bathrooms and kitchens on to their highest settings. This should create a slight 'negative pressure' or suction in the house. The air is being sucked out with the extractor fans, and this will then be replaced by cold air that is dragged into the house through any available gaps or cracks.

If you don't have any extractors, then try waiting for a windy day. The side of the house facing the wind will be under pressure, as the wind forces the air in and there will be negative pressure or suction on the opposite side, pulling air out.

If you don't have an incense holder, just stand a mug or a jar on a plate, so that you catch the ash and have somewhere to stand the incense in to light it. Set fire to the tip of the incense, and when the tip glows gently blow out the flame. You should have a lovely stream of smoke going straight upwards.

I held a black book behind the incense so that you could see the smoke, but the reflections still make it difficult to see. This is the important bit to remember though - heat rises and because the smoke is hot it should stream straight upwards at first and then it will create swirls and eddies as it mixes with the cooler air in the room. It is that first 10cm of smoke that we need to watch. If there is a draught blowing inwards that smoke could be going sidewards or swirling around. You have to hold the incense stick steady and wait for a few seconds for the smoke to settle before you will see it.
As an example the above picture shows the draught coming underneath my gas fire (which was switched off). The smoke is being blown straight across rather than rising upwards. This is a big draught, but is not one that I can seal up. When gas burns it uses up oxygen and needs a constant supply of fresh air. If there is not enough oxygen then carbon monoxide can be formed, which is a deadly odourless gas that can kill. Vents around gas appliances are normal and necessary - don't tamper with them. 
Here is the skirting board close to the front door. The smoke is going straight upwards, so no draughts here, but look what happens a little bit further along. There are definite signs of a draught. I could try sealing up the gap below the skirting board, or take the skirting board off completely and fill any gaps behind it. I could also try taping the joints with an airtight tape before fixing the skirting board back in place.

I am sorry that these are pretty rough photos. I was holding the incense in one hand and taking photos with my other, whilst trying to keep everything steady. There were plenty of draughts around the windows, but it was almost impossible to photograph the smoke against the white PVC frames.

Energy saving no. 6: Inspect seals around windows and re-seal
Even without the incense it is worth inspecting your windows in detail. Close inspection can show where the sealant has come away and is not sticking to the surfaces. I found a little puddle in the corner of my bay window, caused by condensation forming, not from rain getting in. Warm air holds lots of water vapour, but cold air cannot hold as much. When the warm air from the house hits a cold surface or meets a cold draught, it drops some of the moisture. This is called condensation and in places that are regularly damp, mould or mildew will grow. Black mould is often a sign that there is a cold spot or the seals are not keeping the draughts out!

It was interesting to see that in the newest windows installed in 2005, the black mould formed around the seals where the window frame joins the building. The bay window pictured above is probably the best of all the newer windows as it is on a South facing wall. Can you see the black mould on the sealant between the wall and the plastic moulding, and between the moulding and the window frame? The window frame itself is fine though. I couldn't bring myself to photograph the black mould on the North facing windows, because it was really bad, worse than I had realised :-(

Whereas in the older windows that were pre-1999, most of the mould was on the black seal between the glass and the window frame. Can you see that the black seal has shrunk and there are gaps in the corners? This means that the window is no longer sealed double glazing and has lost some of it's insulating properties. There are companies about who can repair these windows, by replacing the glass for A rated glass and re-sealing them.

The newer windows were built to a higher standard, but clearly less care was taken installing them. I seriously need to look at improving the insulation around the window frame and resealing them so they are airtight.

And how is this for condensation? Can you see the big drops of water at the bottom of both the metal locks? Metal is a good conductor of heat, and these locks go right through the door. The freezing air outside is cooling the outer part of the lock and the metal is carrying that cold inside. This is called 'thermal bridging', it provides a shortcut through the insulated material surrounding it, allowing the cold to get in. These doors were installed in 2005 and are 'FENSA approved' which means that they should have been built to meet section 4 and 7 of the 2000 Building Regulations and come with a 10 year guarantee. I won't make you read the Building Regs, which are very long-winded, but in essence it boils down to this.....

Reasonable provision shall be made for the conservation of fuel and power in buildings by
(a) limiting heat gains and losses
    (i) through thermal elements and other parts of the building fabric;

So my windows should limit heat being lost through them (and around them), to improve energy efficiency. If you compare them to the old single glazed windows that were there before, then they certainly are far better, but it is clear to see that there is still a lot of room for improvement. Building regulations have become tighter regarding energy efficiency since then, but has that filtered down to the small replacement window companies yet? Let me know if you have had similar problems.

There was one other lovely quote from the Building regs. that I need to share. All building work shall be carried out....

".....(b) in a workmanlike manner. "

Hmmm......I don't think the workmen have the same idea of a "workmanlike" manner as the suited individuals who wrote this ;-)

So there is lots of detective work that you can carry out in your home. My advice is to just look at one room at a time, maybe starting with the coldest place, or where you spend the most time and can feel the draughts. Then you won't get overwhelmed! I'm going to be sealing up some of the draughts in future posts, but some councils or Transition groups run 'Draught Busting sessions', to show you how it's done, so look out for these in your local area.

I am trying to keep things clear and simple, so please let me know if I get too technical or fail to explain something. Likewise if I'm boring you by explaining the obvious. Thanks :-)

Oh careful with the incense sticks - please don't singe or set fire to your curtains or carpets or burn yourself. Make sure the area is clear, and keep the plate handy to knock the ash onto before it falls.


  1. you got ripped at wilko's , poundland do them 60 for £1 :P

    Im going to read this guide because I am going nuts with a draught...

    1. Thanks. I know where to look next time....if I ever run out ;-)