We are frequently asked how to reduce heating bills on a wide range of properties. The cost of gas, oil and electricity has increased over time and our heating bills are becoming more of a concern. They will continue along that path unless we do something about our properties or the way we live in them.
You could simply decide not to switch on your boiler but that will ultimately leave you with an uncomfortable internal air temperature during cold winter periods. We often see properties with a gas boiler permanently switched off, or the dial timer set to only provide heating for a couple of short periods per day. There are growing concerns with the cost of gas boilers and so many occupiers appear to avoid using the boiler for fear of a sky-high bill at the end of the month.
There are many types of heating systems available; gas boilers, oil boilers, electric heaters being more traditional options, but modern technology brings us ‘Air Source Heat Pumps’, ‘Mechanical Ventilation Heat Recovery Units’ ‘Geo-thermal systems’ use a more sustainable source of energy.
Rather than ‘which heating system should I install?’, we should be asking ourselves ‘how do we create an affordable living environment?’ The answer to this question is not whether we use gas, oil or electric forms of heating, but how can we alter our properties to reduce the amount of heating required?
Think of ‘heat loss’ as the enemy. This is your battle and you need to be prepared to fight on two fronts to win the war. So how do we reduce heating bills? Fight these two battles and you will be on the way to total victory;
a. If the external envelope of our property is not insulated properly, there will be a high rate of heat loss. Therefore, it is very important that we first make sure our properties have at least the minimum requirements of insulation to ensure our heating systems are running economically.
b. We need to apply insulation to the external envelope of our properties. Roofs, External Walls, Windows and External Doors are obvious external elements, although we also need to insulate ground floor structures to minimise heat loss through all elements of the building.
c. Insulating materials come in many forms. Mineral wool or quilt insulation is the most common and can be positioned between rafters or joists without too much difficultly. This form of insulation needs to be very thick to be effective and can sag or drop out of the space it has been installed, leaving large air gaps. A ridged board insulation can be cut to fit between joists of rafters and out performs quilt insulation with significantly thinner layers. There are lightweight insulated aggregates for ground floors, multi-foil insulations and vacuum-sealed insulation boards as a modern alternative. Each product has a different level of performance, therefore the question ‘which product should I install?’ is a balance between performance and cost. There are literally so many types of insulation we can use in our properties, in some instances we may not have a choice, site restrictions limit the use or you may need a high performing insulation to achieve a target thermal value.
d. No matter which type of insulation you purchase, if it is not installed correctly then it won’t perform. Defects with condensation, mould and cold spots are generally a result of poor installation. Meaning air gaps between insulating materials or poorly detailed parts of the building, junctions between walls and roofs leading to what we commonly refer to as ‘cold bridging’. It is essential that all types of insulation is installed correctly to avoid any gaps and cold spots leading to internal defects and of course, less performance.
e. Building regulations will dictate the minimum level of insulation you will need to install. If we are altering a ‘thermal element’, then you will need building control permission and should apply for a licence. A ‘thermal element’ means anything external including ground floors, so replacing your roof coverings, external render or internal plaster will be deemed ‘controlled work’ and a licence is required. Building Control will want to know that your repair / replacement achieves the minimal standard. So the question really is ‘how much do you want to install?’. Do you want to comply with the minimum standards or out perform them? I always tell clients to invest their money on insulation. This is an expensive product, but once installed it does not need to be maintained and has an apparent unlimited life-cycle. So how much insulation would I install in my own property? (I am frequently asked this) and my common answer is that I would install as much as I possibly could. Imagine a world where we don’t need a boiler, is that possible? It most certainly is. Passive House Standards are designed to create a property which is air tight, insulated and detailed to a very high standard. Meaning extremely low levels of heat loss to the point that a heat source is not required, we generate our own heating and keep it in the property.
f. If you want to reduce your heating bills, don’t look at your boiler, you need to look at your property. Where there is a lack of insulation there is room for an upgrade. You might think, ‘my property is more than 100 years old and there is nothing I can do’. There are limitations with older or listed buildings, however there is always options to upgrade them and the slightest thermal upgrade will help maintain a suitable thermal comfort for a reduced cost.
2) Cold Air Infiltration is really a clever term meaning a draught. You might think this only relates to poorly fitted window casements or external doors, but it is not that simple.
a. It goes without saying that if you have a draught, cold air will pass through the external element into your accommodation and the room itself will prove difficult to maintain a level of thermal comfort. How many times have you heard people complaining about feeling a draught and yet can’t quite figure out where it comes from. True, poorly fitted windows and doors are the main culprit so you should start there. They are obvious parts of the construction but we normally forget important details like keyholes, cat flaps, letter boxes; these are all parts of the external envelope that need to be looked at and upgraded to minimise any cold air infiltration.
b. It can happen on any part of the external envelope, which also means the ground floor structure. Suspended floors have ventilation beneath. The ventilation can pass through the floor structure and the thermal photograph shows dark lines from the junction between floor and skirting board which is the best visual aid to show cold air infiltration. Dormer windows and roof lights, eaves cupboards or roof junctions are all areas to look closely at for draughts. Even ceiling lights, down lighters which cut a hole in the plasterboard and then let cold air through the internal lining. It can happen almost anywhere on a property, anything connected with the external envelope, even pipes or cables passing through the walls. Perhaps not quite so obvious but still an important part of the construction we can forget.
c. Silicone sealant is the main tool used to prevent cold air infiltration on awkward details like gaps in skirting’s and floors, although that is really a retrospective solution. If you are in the process of construction, you should ensure the details are correctly formed, vapour control layers and sealant tape on window and door frames to the wall structure before applying the internal reveals will be a massive improvement. Windows and doors can have draught exclusion tapes but really if they are poorly fitted, it will be best to replace them or apply a secondary glazing. It is extremely important to minimise cold air infiltration through the external envelope if you want to minimise heat loss.
By now you will have been looking around your property for areas to improve. Heat loss is not really something you can see happening unless you have a thermal camera and these are very expensive. The tiniest detail can be the biggest problem, so if you truly want to reduce your heating bills, look for ways to upgrade your building before deciding to install the latest ‘green energy’ boiler.
Gary Naftel BSc(Hons) MCIArb MRICS
The information in this Coffee Break article is intended for guidance only. The authors cannot accept any liability for any loss or damage which may result from the use of this article.