While not all buildings can be upgraded to the energy efficiency standards of modern buildings, significant carbon savings can be achieved through specialist solutions, which balance out the energy savings from introducing often unsuitable modern technologies and materials designed to last only 30 years.
Malene Holmsgaard, who was previously Market Director of WSP’s Centre for Building Preservation in Denmark, explains, “We calculate the carbon and energy savings of our proposed solutions and take into consideration the building fabric. Often it turns out that, for example, while you can’t insulate the façade of a building due to listed building regulations, and you can’t put insulation on the inside because of the risk of condensation and mould, the original structure of a robust brick building is good enough as it is. Because the amount of carbon, it would cost to insulate it, and the accelerated maintenance due to freeze-thaw of the brickwork would outweigh the gains of the insulation process.”
Listed building regulations also frequently prevent the replacement of draughty windows. “The seemingly ideal solution would be to replace old wooden windows with aluminium frames and thermal glazing,” Holmsgaard continues. “But that’s normally not allowed and, in any case, thermal glazing needs replacing every thirty years. We have calculated in collaboration with the Technical University of Denmark that by retaining and properly maintaining the original windows, and installing secondary glazing, you get the required level of insulation and significant carbon reductions. At the same time, you achieve savings on the total costs and considerably reduce consumption of resources, since the original windows have a lifetime span of more than 100 years.
And it turns out, there is another benefit. Reusing existing materials if correctly maintained and preserved with traditional products fits in with circular economy principles. Not only does that wood in the windows last longer, but when it finally does need replacing, by not ‘infecting’ it with un-recyclable products such as modern paint but treating it in the traditional way with linseed oil, it can be reused rather than going to land fill.