Insulation Properties of Older Houses: Investigation with a thermal imaging camera

Older houses pose particular challenges with regard to thermal efficiency and sustainability. For this reason Sarah and myself found it extremely useful to borrow the thermal imaging camera to investigate our house- Culhams Farmhouse. The farmhouse was built in 1840 and the original part of the house has solid brick walls although several more modern extensions have cavities and mostly meet today’s building regulation standards. Windows in the original house have thick oak frames and single glazed lead mullions. The property is Grade 2 listed so anything we do has to meet the approval of the conservation officer. Originally the house was built without a damp proof course, but a chemical course was inserted over 40 years ago much to the disapproval of the conservation officer who told us that this should not have been allowed. We don’t appear to have any significant damp issues. Today the house has a modern gas central heating system (boiler replaced 18 months ago) which is supplemented by two log burners (both replaced recently and meet today’s standards) and an open fire. I have purchased a wood moisture meter to ensure I only burn seasoned wood.

Another part of the thermal efficiency jigsaw is how we use the property. It’s relatively large and there are only the two of us rattling around in it so throughout the winter half of it is unused and unheated apart from Xmas. Two downstairs reception rooms are mostly unheated- but the radiators and log fires can bring them up to temperature quite quickly in the event they are needed. Similarly, only one of the bedrooms and both bathrooms have background heating the rest being left completely unheated. The house has two large, cavernous lofts and I have improved the depth of insulation on the one above our bedroom, but the other larger loft doesn’t meet today’s standard for thickness of insulation.

Having set the scene what did the thermal imaging camera reveal? We borrowed it on a cold and frosty night when there was a log fire in the lounge log burner and the radiators were working in the rooms we heat. The camera is very sophisticated with a large instruction manual but in simplistic mode you can forget all this and switch it on then pull and hold the trigger. The screen now reveals the thermal image, and you can walk round the outside of the property to investigate its thermal properties. Black or grey is good but yellow or orange is bad suggesting significant heat loss and red is awfully bad.

How did Culhams Farmhouse fare? The good news is (and somewhat surprising) that the walls of the original structure and all of the roofs were black showing no appreciable heat leakage. Rather surprising is that the image of the downstairs cloakroom, a 1980s addition with a conventional cavity wall construction, clearly showed the outline of its radiator in orange suggesting much greater heat loss from the newer construction. The bad news was the windows, where all of the original window openings with single glazing, showed significant heat loss. The camera was also effective in identifying heat loss through drafts. We have a new extension completed 18 months ago comprising a large kitchen extension and involved excavation of the original kitchen to install underfloor heating which is modern and efficient. (I know that earlier I said the house is too big so you might wonder why we extended- it’s a long story but in essence the space we had wasn’t in the right place). As an aside the kitchen refurbishment made a major contribution to reducing our carbon footprint as we got rid of the solid fuel AGA which used to run 24/7 throughout three seasons and consumed anthracite at an alarming rate. The kitchen extension was built with an insulated cavity wall and no problems were detected here. However, we had windows with solid oak surrounds and also tri-fold doors with solid oak frames. We were warned these might shrink and cause drafts and these were clearly visible on the camera showing as a thin strip of orange along the hinged joints. The other major draft leakage was from the old front door. This is rarely used but is the original oak door, 180 years old. Its warped and has been for years but we have a curtain we can draw across it.

So what are the next steps having seen the thermal imaging? Well, the apparent loss of heat through the solid walls was a huge relief. Solid walls can be a major problem in older properties and options are limited- wall cladding is ugly and, in any event, wouldn’t be permitted in a listed building. Thankfully, the walls at Culhams  are thick (four bricks thick in fact) greater than many older properties and thicker than modern cavity construction albeit without the benefit of high performance insulation. I’m surprised about heat loss through the downstairs cloakroom- I would have expected a 1980s construction to have insulation in the cavity but perhaps not. I will fit a thermostatic valve on the radiator and lower the temperature. I have just bought a load of draft excluder and have started to fix the worst problems. Then there is the question of the single glazed windows! Some were replaced a few years back by a previous owner and had to be handmade- the bill was huge. There is no easy answer to this but I am looking a the possibility of secondary glazing although Sarah and I have yet to agree on this radical step. In the meantime we will continue to draw the thick curtains in the winter months.

All in all, the thermal imaging experience was very good. It provided some reassurance but also focussed attention on where the quick wins are for thermal efficiency. I would recommend it to everyone.


Paul Roper

Living with an Electric Car

I love my electric car.  I’ve had a Renault Zoe for 7 years now and it still makes my smile every time I put my foot down and pull silently away from the lights faster than almost any other car.    In the word used for Rolls Royces – it has waftability.


The first question I am always asked, is how far it can get on a charge. 

Mine is an early electric car, and the range is 70-80 miles depending on driving conditions and the temperature.   There are very few days when I need to travel further than 70 miles.    Almost every charge is done at home.  I have made it to Portsmouth, Bath and Cambridge  – and all those places will come easily within range when I come to replace it,  as newer models all have ranges in excess of 200 miles.  But at the moment longer journeys need a little bit of planning, although this is getting easier as the number of charging points increases.

If you are thinking about an electric car, it is worth looking at electricity tariffs designed for the electric car owner, which don’t come up on comparison websites.  I’m currently using Octopus Go, which gives me a few hours of very cheap charging overnight, so a full charge costs less than £1.

I do like the green credentials: lower CO2 emissions and no pollution, I love the silence that allows me to listen to music without the engine as background noise, but that’s not the main reason that I would recommend an electric car.  The main reason is the driveability.  It is just so nice to have a car that responds so quickly and smoothly when you put your foot down.  It’s very difficult not to be a boy racer away from the lights.

Energy Efficiency in Heritage Buildings

On 8 April I attended a talk by Daniel Ayre, from BDBC’s planning department, on energy efficiency in Historic Buildings.  Here’s my take on what he had to say.

Many of the houses in Silchester are in the Conservation Area, or are historic or notable buildings, and they require some different energy efficiency measures from more modern buildings.  Historic buildings work differently from modern buildings.  Modern buildings are “sealed units” whereas  historic buildings “breath”, letting moisture and air in at night and out during the day.  Any change to this can disrupt the function of the building and cause problems. For example, there may be condensation on the windows in the morning.  However, if you change the windows and stop the condensation, then you have to consider where  the moisture is going instead.  It may be somewhere less easy to deal with.   Similarly any wall insulation that stops the building breathing is likely to do more harm than good.

Although when we talk about energy efficiency, we are usually thinking about heating and electricity, Daniel observed that for buildings there are actually three sorts of energy that we should consider:

  • Embodied Energy – the energy of construction locked up in the building
  • Operational Energy – heating, lighting etc
  • Demolition Energy – the cost of disposal

A historic building has a lot of embodied energy, stored in some cases for hundreds of years and it is not necessarily energy efficient to demolish that to make small savings in operational energy.  For this reason, as well as the need to conserve the character of the area, the council will often recommend repair to existing structures rather than replacement.   Thinking again about the windows: many people think that energy efficiency requires moving to modern double-glazed windows.  This is possibly true if the existing windows are beyond repair (say, more than 55% of the frames would need replacement), but the energy in constructing a modern double glazed window in a factory far outweighs the cost of a local joiner building a replacement single-glazed unit.  And, when it fails, a double glazed window will need replacing in it’s entirety using yet more energy, a single-glazed pane of glass can be replaced.

 Energy efficiency measures that you might consider include:

  • keep the building in a good state of repair, and prevent draughts
  • repair what you have, rather than replacing with new
  • breathable insulation in the loft
  • secondary glazing
  • consider a heat pump, the steady heat can be better for a historic building than the heat-cool cycle of existing heating systems

Finally, historic buildings are often inherently more energy efficient than they appear, staying warmer in winter and cooler in summer than some modern properties.  So if you are lucky enough to have a historic property, enjoy it!