More snow…and a real test for Nansulate and the heat source pump.

More snow? Well, that’s a surprise, it being winter and all that, at least as the media would have it. With the first cold snap presiding over Christmas and the New Year came the first real test for the heat source pump installed last March by Highland Alternative Energy (HAEL) together with the Nansulate liquid insulation we have been applying steadily over the last year. The pump performed beautifully, keeping most (not all) of the house at a comfortable 18 degrees Centigrade when outside temperatures hit minus 10 to minus 12 degrees at night and struggled to reach minus 4 degrees during the day.  The drive was ice, the car was stored in the field at the top of the drive because access was impossible and conditions were treacherous.

As I have written in my blog in the past, the key to making real savings with energy efficient devices (such as our air to water heat source pump) is to insulate the home as much as humanly possible as part of the energy efficiency strategy. HAEL emphasises the need for insulation but it’s not always practical to install the good old fashioned stuff or even modern systems such as Kingspan. As we well know because our house consists of what is, in effect, two different types of construction: the original Scottish Highland style cottage with thick stone walls and hipped roof with a loft suitable for traditional insulation and a large flat roof extension of considerable footprint but with little scope for using traditional insulation; the roof being little more than a skin of thick timber planking with a reinforced fibre glass top to keep the water (and snow) out. No fibre or foam insulation can be placed in the 250mm cavity between outer skin and the ceiling because this space is needed for ventilation. Like the layout cabin, this presents some challenges to insulate effectively.

Sarah, when searching the internet for ideas one evening, discovered Nansulate as a solution for insulating the layout cabin (which was completed successfully before layout construction advanced too much. Nansulate is a liquid insulation which looks something like acrylic wood varnish and can be applied to many types of surface including wood, plaster board, painted surfaces and even glass if preparation is done correctly. A minimum of three thin coats is required and it can take 60 days to cure depending on prevailing conditions. Perhaps the hardest thing to reconcile is how such a thin coating can provide so much insulation benefit. Well, engineers are conditioned to thinking ‘thicker the better’ and that’s fine for traditional materials. Yet, As far as the cabin is concerned, Nansulate has enabled me to reduce the number of heaters from two to one 2kW radiator. Previously, one was used for background heat whilst the other would be switched on to bring the temperature up to a comfortable level. Now, only a single Delonghi ‘Dragon’ is used and that keeps the cabin at 15 degrees Centigrade, with excellent cost saving.

Nansulate is clearly the ideal solution insulating the flat roofed extension to the house based on our experience with the cabin and we applied it to ceilings and walls with a traditional paint roller of medium pile – over the original painted surfaces. The work was done in one bedroom, the office and kitchen with some interesting results. For example, the bedroom has little heating from a single (inadequate) radiator. Yet when the outside temperature is around 5 degrees Centigrade, typical for January here on the Moray Firth coast, the internal temperature sits around 14 degrees – fine for a bedroom. The front office and kitchen maintains a comfortable 18 to 20 degrees Centigrade, falling by a few degrees when the outside temperatures plunged to minus 12 as it did during the recent cold snap.

Nansulate together with the heat source pump has made supplementary heating in the afore mentioned bedroom unnecessary; the oil filled radiator once used in there is now redundant. The main part of the house, which has 450mm of loft insulation and Nansulate applied to the walls, also requires no further heating on a day to day basis; the heat source pump keeping the house at a very comfortable back ground temperature 24/7.

Whilst it is difficult to isolate just one factor in our success in keeping the house warm without spending a fortune during the recent cold snap, here is little doubt that the heat source pump has maintained an excellent level of heat, 24/7, unlike a conventional timer controlled heating system which heats like mad then shuts off for a while before kicking in again or relies on a period of low energy tariffs to boost heat in the house before shutting down and allowing temperatures to fall away (storage heaters for example).

However, Nansulate has been a big help in retaining that hard-gained heat. Before Nansulate was applied to the living room walls and other walls in the main part of the house, temperatures took more time to come up to a higher level when heating was turned up. Now Nansulate is installed, time to raise the temperature from 18 to 22 degrees Centigrade is much reduced, effectively reducing the heating load on the heat source pump or the amount of wood used on a wood burning stove.

During the cold snap, we recorded temperature differentials between the inside and outside during a typical night time temperature of minus 10 recorded  between Christmas and New Year:

  • Bedroom: 12 degrees internally with minimal heating.
  • Living room: 21 degrees internally – 19 degrees with heat source pump, 21 degrees with low level use of a wood burning stove and radiators turned off.
  • Kitchen: 14 degrees.
  • Cabin: 14 degrees.

During the day with a recorded external temperature of minus 5:

  • Bedroom: 13.5 degrees internally with minimal heating.
  • Living room: Same result, with 21 degrees internally – 19 degrees with heat source pump, 21 degrees with low level use of a wood burning stove and radiators turned off.
  • Kitchen: 16 degrees.
  • Cabin: 14 degrees.

Our electricity consumption for heating using the heat source pump is likely to be around £1200 for the 12 months covering this colder than usual winter (for a single storey home of 160 square metres, 1/3rd of which is the flat roof extension), still higher than it should be, but much lower than in previous years with less cold weather. The HAEL engineer we have regular contact with believes that figure should be much lower and his view is that we need to take yet more steps to insulate the house, something I agree with. Nonetheless,  Nansulate has performed well where applied, and a further demonstration of this was observed today when it was turned off by the HAEL engineer for about 5 hours whilst he fine tuned the machine for further performance enhancement. The front office, with Nansulate on walls and ceiling only lost 2.5 degrees during that time, falling from 19 to 16.5. The external temperature was only 2 degrees Centigrade. It should be noted that the office also has a large glass door, so performance was pretty good!

So, the moral of the story is: Insulate, insulate, insulate!!

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