Heritage Retrofit

12 BCD SPECIAL REPORT ON HERITAGE RETROFIT FIRST ANNUAL EDITION • then look at generating the remaining energy needs from renewable sources. This approach ensures that the ‘low- hanging fruit’ are chosen first, which often yields comparable benefits to more complex, expensive, or harder-to- implement measures. In a heritage dwelling, the energy hierarchy should be considered within a ‘whole house’ approach – that is, understanding the home as a system, and systematically thinking through whether changes made to some elements or functions will impact on others. For example, draught-proofing will decrease the movement of air in the home, so consider fitting controlled ventilation. Chapter 2 of Warmer Bath (see Further Information), ‘Deciding what to do’, explores how to reduce energy use and improve energy efficiency in a traditional dwelling, and compares measures to each other in terms of cost and carbon cost-effectiveness. Further guidance on the appropriate choice of measures will be available from a forthcoming Historic England advice note, which CSE has helped to develop and which will set out good practice on the sustainable energy retrofit of traditional dwellings. EASY WINS With reference to the above, it is crucial that retrofit plans start with the desired outcome, not with a specific measure. It can be useful to rank desired outcomes because this can also guide the best approach. Examples of desired outcomes are: • a warmer home • reduced running costs • increased market value. Thinking about a Georgian house with sizeable windows against this list of desired outcomes, the measure that might initially spring to mind could be double glazing. But the key question is always the same: ‘Is there something simpler, less invasive, and more cost-effective that I can do first?’ In this case, there is almost certainly a cheaper, less invasive way to achieve all three outcomes. Replacing original Georgian windows with modern double glazing is unlikely to have a positive impact on the market value of the home in any case, since original features are so highly prized. It is also unlikely to be acceptable in heritage terms if the building is protected in any way. It may be that timber, slim-line double glazing units could be acceptable, but these are likely to be astronomically expensive. However, a combination of other measures might achieve the same desired outcomes with less harm (for example draught-proofing the original windows, in combination with fitting thermal blinds and curtains with the installation of secondary glazing and the renovation of existing internal shutters). Ideally, energy-saving measures should also contribute to conserving the building’s significance, including undertaking necessary remedial and maintenance work, and might even enhance it by emphasising historic features and the ways in which they illustrate the building’s history and use. CHOOSING APPROPRIATE MEASURES Behaviour change is always the cheapest measure, and should always be considered first. Better control over heating and lighting systems can sometimes be expensive but can reap rewards in the long run (fitting more efficient boilers, heating controls and timing systems). The imminent roll-out of smart meters bridges the behaviour and control themes, and ‘queue jumping’ is sometimes possible so householders are encouraged to contact their utility provider to see whether they can have a smart meter installed. Daily interaction with the data from a smart meter has been shown to alter energy-use behaviour and cut energy costs without any other measures being implemented. Beyond behaviour change and better controls, we move into the realms of physical changes to the home. Breaking down the home into its constituent elements, the types of interventions that can be deployed can be ranked from least to most invasive (green to red) which, in general terms, also means least to most expensive. If all the measures coloured green in the table on page 11 were deployed (alongside behaviour change and better controls), the likely energy savings and comfort improvements would be significant. In terms of value for money they would be likely to cost less in total than a single red measure in the table. Detailed guidance on how a range of measures can interact with each other can be found in the excellent Responsible Retrofit Guidance Wheel , produced by the Sustainable Traditional Buildings Alliance. This allows the user to select a range of measures and consider how they might interact with each other and what the risks to both the physical fabric and historic significance of the building might be. Fuel poverty levels are higher in traditional homes than in the wider housing stock, the costs of energy are rising almost inexorably, national retrofit policy is seemingly in disarray following the collapse of the Green Deal, and huge cuts to local authority budgets mean that conservation specialists are thin on the ground. It has never been more important to ensure that householders have access to useful guidance on making the right choices on how to make traditional buildings more energy efficient. The UK’s heritage housing stock is an Produced by the Sustainable Traditional Buildings Alliance, the Responsible Retrofit Guidance Wheel helps users to evaluate how a range of measures might interact with each other and what risks they could pose to a given building’s physical fabric and historic significance. (Image: STBA)