The importance of addressing the existing housing stock in the UK as a key part of achieving our challenging goals as defined in the Climate Change Act is unarguable. The fact that it is frighteningly difficult does not make it any the less necessary. We have a disparate housing stock reflecting a long history of construction techniques, designs and materials. We know that at the key date of 2050, 80% of the houses that will be in use will have already been constructed today.
The social housing sector has a good record in delivering improvement programmes which have already advanced estates standards beyond other sectors. Nonetheless, the challenge of retro-fitting improvements remains daunting, and particularly where there is still a debate regarding competing technologies in the heat sector. Social landlords have the benefit of long term ownership and leasing agreements and this certainly is positive in looking at return on investments. The sector can also look at the returns in non-financial terms such as health benefits and the reduction of fuel poverty.
In my opinion, the simpler the proposition, then the better prospect of success and one of the real failings in the construction sector has been the inability to describe actions in simple language and to describe benefits in measured ways. The honest truth and absolute transparency is what we all need. Often it seems that competing interests spend their time criticising others rather than promoting their own solutions. I have heard people say ‘householders don’t want heat pumps’. Households don’t want boilers either; they want warm homes at a reasonable price with the minimum of fuss.
Fitting a highly efficient heat engine will be hugely compromised if it is connected to an inefficient heat distribution system.
Any retro-fit scheme should start with maximising the efficiency of the building fabric, this is undeniable. Reducing energy demand in the first place has to be the most effective way forward. Of course, some buildings will be more difficult to treat than others but getting the order of work right in the first place is important since reduction in heat demand will directly affect the heat source choice. The cheapest and least damaging energy is the energy that we don’t use.
When considering heating technologies there are many influencing factors including budget, locality and availability. There is no silver bullet, but the consideration must always look at the whole system in the whole building. Fitting a highly efficient heat engine will be hugely compromised if it is connected to an inefficient heat distribution system. Similarly the system needs to be controlled suitably so that comfort can be achieved where it and when is needed.
Renewables are certainly getting a lot of current attention and they can be very effective in the right situation.
Ground Source Heat Pumps are a well established technology across the world and, in particular, in Scandinavia. The benefits are high coefficients of performance and consistency of performance. This is because the ground temperature varies very little at depths of a meter or more. Collectors may be fitted vertically or horizontally. The problems are that they are expensive to install with the additional civil works and if horizontal collectors are specified then a relatively large are of land is required. Drilling is also relatively expensive for vertical collectors. However there have many examples using shared collectors in GSHP systems, even in the case of blocks of flats where compact units may be used. Heat pumps are generally cheap to maintain.
Air Source Heat Pumps are cheaper and easier to install than GSHP and the main unit is fitted externally since the heat pump uses the air as the heat source. This does mean that ASHP performance varies with the air temperature but most units are designed to work well across most UK temperatures. A well sited heat pump should have a coefficient of performance around 3:1. Issues with ASHPs relate to installations in poorly insulated buildings. Other considerations include noise issues and the availability of a suitable siting area.
Heat pumps work at lower temperatures than a boiler and therefore, if fitted to existing distribution systems then radiators my need to replaced. The environmental benefit of a heat pump depends on the carbon intensity of electricity which is declining year on year as a larger proportion of electricity generation comes from renewables and low carbon sources. It is also true that electricity is 4 times as expensive as gas per kWh, and this will skew price comparisons with existing gas boiler systems.
Solar Thermal panels provide domestic hot water by capturing the heat from the sun and storing it in a suitable cylinder. They were rather neglected in the tidal wave of demand which came with Solar Photovoltaics caused by the Feed In Tariff incentive scheme. Solar thermal works best on a south facing roof but is obviously affected by shading and cloudy weather. Although solar thermal panels do not require direct sunlight to work, their efficiency is reduced. The return is limited by the amount of hot water required by the household.
Biomass boilers use wood pellets as fuel and deliver the heat through traditional radiator distribution systems. They have been most popular in rural locations which may not have access to the gas network. They tend to be large units and will require storage facilities for the pellets which have to be from specified suppliers. There has been a drive to reduce particulates which are produced from the combustion of wood but careful thought may be required in densely populated areas.
Currently all these renewable technologies are able to receive funding through the Renewable Heat Incentive.
Solar Photovoltaic panels use sunlight to generate electricity. However, since the electricity is generated during daylight hours when homes may not be inhabited it is sometimes difficult to demonstrate savings. Storage in locally sited batteries is possible but may be cost prohibitive.
Any understanding of improvement can only be made by a detailed understanding of the current situation.
Any ‘improvements’ will also be defined by how well the work is carried out. This is achieved by clearly defined and published expectations; a well trained and experienced workforce; detailed monitoring of work completed; and the definition of benefits linked to rewards.
Lastly, there needs to be a policy for the most complex component in any building, the inhabitants. Tenants need to be actively engaged in any retro-fit programme. There needs to be clear advice managing expectations and giving real, hands-on instruction on use and best practice. The honest truth is that many people don’t want the disruption caused by retro-fit work and they need to shown some true, quantifiable benefits.
The truth is that if we are to achieve our carbon targets then we will have to stop burning fossil fuels and, as yet, there are no solutions that are without huge challenges. Social Landlords can be certain that standards will continue to become more stringent and the timing of investment is key.
