Its that time of year, the clocks go back, the temperature starts to drop, and the heating is switched on for the first time since April. With the some of the leakiest homes in Europe, often the heat we generate in our homes is lost into the atmosphere without doing anything meaningful with regards to our thermal comfort. So how do we improve our homes, and ultimately stay warm this winter without spending excessively? Well, there are two answers to this question depending on budgets and approach. The first approach is to accept the thermal performance of your home ‘as is’ and look for more effective or cheaper means to actively heat the property. This is particularly pertinent for those of us in period properties, where the scope to change the thermal make-up of the building is limited, either due to conservation restrictions, or due to the desire to maintain the current buidling aesthetics.
Conventional gas or oil heating systems
For those of us with conventional gas or oil heating systems, we are often at the mercy of our energy suppliers – however we can shop around to find the best deals, for example Money Saving Expert. But if we are already on the best deal possible what then? Well we can look to how our heating system operates. With traditional combi-boilers, it is often the case that we are not operating our boilers at their most effective setting. If you are the owner of a conventional condensing boiler, which is estimated to be over 74% of us, be aware that the default setting for these, is often not the most efficient one. Condenser boilers work by taking the exhaust gases from the combustion process and having a second go at extracting energy from these gases by re-condensing the water vapour in them (taking example of a brilliant bit of physics – the latent heat of condensation). Unfortunately, if the initial heating demand is set to too high a temperature, this wont work properly and the efficiency is greatly reduced – you are essentially spending significantly more money to generate only a little more heat. By reducing the boiler temperature setting it is possible to increase the boiler efficiency, but still have sufficient heat going to radiators to provide warmth.
For those of us using boilers to heat hot water tanks beware, the tank will periodically need to be heated to 60°C or above to prevent the formation of legionella bacteria, which can be severely hazardous to health. The Heating Hub provide an excellent article on this, which is well worth a read.
Even if you do adjust your boiler setting, take care as tradespeople servicing the boiler will often reset it back to the maximum flow temperature. One brilliant side effect of reducing your boiler outflow temperature, is you can also go one step further and drop the temperature to a level that would be equivalent to running your home from a heat-pump, which generally operates around a flow temperature of 50°C. By running such low temperatures (during a particularly cold spell) you can ascertain which rooms have radiators that are potentially too small and not heat-pump ready. This is something at Red Fox that we can assess analytically as part of our home heat loss survey.
Loft Spaces
It’s highly likely that conventional boiler systems will eventually be replaced for the majority of us by air source heat pumps. Whilst it’s a myth that heat-pumps wont work in older, badly insulated homes, it’s this engineer’s view that a ‘fabric-first’ approach is a sensible way forward to address a leaky home. This means installing, as much as is feasible, insulation and air management systems to prevent the heat we have in our homes from leaving during cold external conditions. This warmth can either by actively generated (e.g. from a boiler, or fire place) or passively generated, such as solar gain through windows, or even body heat! Logically, this also means the installation and running costs for any future heating systems are reduced, as we need to generate less heat to maintain the same level of temperature in the dwelling. The obvious place to start with insulation is in loft spaces, where even modest increases in insulation thickness can lead to significant reductions in heat loss (after all heat rises). Generally speaking, in conventional converted lofts, 270mm of mineral wool insulation will be sufficient to comply with building regulations, but most importantly reduce heat loss to an acceptable level.
Walls
Next on the hit list would be walls, and checking (if they are cavity) whether they have been filled with cavity wall insulation. This is not always easy, but tell-tale patches at regular intervals in the mortar will be strong evidence that cavity wall insulation has been fitted to older homes. Failing this, borescope or thermal imaging inspection are also good ways to check if this is present, noting that older types of cavity wall injection have a tendency to slump over time, which degrades overall thermal performance. For newer homes, generally those built in the 1970s and later, cavity walls are typically a given, though the thickness and performance of the insulation inside them varies.
Windows and Doors
Finally, windows and doors. Varying from single, to double and even triple, windows (and doors) are usually the weak point in the building thermal envelope. Most modern windows (post 2002) have a significant gap between the panes which is filled with a low thermal conductivity gas, such as Argon. For windows that pre-date these, it’s often worth looking at upgrades where possible, or as one potential low-cost mitigation, employing the use of secondary glazing. This acts to create another area of trapped air near the window, which though not efficient as trapped Argon, acts limit convective heat exchange with the room. Checking door and window seals with the back of a hand on cold windy days is also a good method to check how they are performing, and whether they need to be replaced. Draught excluders on doors are also another well-known technique as are thermally lined curtains.
There are of course many more means by which we can understand and address heat loss, but hopefully this article provides a few pointers. Of course, a Red Fox thermal imaging survey is also an ideal way to identify the majority of issues identified above and start the process of reducing our heating demands and associated carbon footprints.