Four reasons why: Decarbonising historic buildings is not straightforward

Heritage buildings are monuments to the richness and diversity of history, and constitute vital cultural assets. As the need to reduce carbon emissions across the built environment intensifies, professionals must strike a delicate balance between conservation and environmentalism. Last month, we brought together four expert practitioners from across the world to discuss the challenge.

Heritage buildings are diverse, making consistent approaches to decarbonisation complicated

This, according to Dr Duncan Philips, Director and Founder, Listed Building Surveys can lead to friction between government and conservationists. “We’re confronted with government on one hand saying, ‘reduce your carbon emissions’ and, on the other side of the coin, conservationists trying to protect the buildings. There is usually conflict between the two groups.”

The problem, it seems, is threefold. Conservation protocols differ according to the age of the building, the methods and materials used in construction, and specific locational factors. Of the latter, complex governmental and bureaucratic structures can be difficult to navigate.

Warren Adams, Preservation Officer for the City of Miami notes that problems often arise when public agencies have subtly different priorities: “In the United States, there are three levels of historic preservation: the federal division, the state division and certified local governments.”

Urbanisation and pressures caused by natural events may lead to the loss of historic sites

Warren Adams explains that, in Miami, “Developers really fail to see, in most cases, the value of historic preservation. A mix of older and newer buildings can have benefits for residential and commercial areas.”

Candy Chan is Director of Property Conservation Co. Ltd and Vice-President of the Hong Kong Institute of Architectural Conservationists. She notes that the city’s extreme density and growing population has forced developers to look at novel means of preserving heritage buildings.

“The redevelopment potential is a matter of concern. However, in recent years, developers have looked into the possibility of keeping part of the historic building and merging it with the new development.”

Robin Miller, Director of Origin Consultants, sets out a very different series of environmental concerns. “New Zealand sits on the Pacific Ring of Fire and as people will have seen, has experienced significant earthquakes. That has really focused public opinion on unreinforced masonry buildings. As Christchurch showed, a city centre can suffer substantial damage in just a few minutes from an earthquake.”

As a result, he goes onto say, “There has been a recent change in legislation to what are called ‘Earthquake Prone Building Notices’. These have been served on owners of unreinforced masonry buildings, giving them between seven-and-a-half and 35-and-a-half years – depending on the risk – to either strengthen or demolish their building.” Unsurprisingly, a sizeable proportion of Christchurch’s earthquake prone buildings are historic. As a result, numerous unique structures will be significantly altered from their original form, while others could be lost entirely.

Global sustainability targets will be hard to meet given the diversity of the global historic building stock and variety of policy approaches

Robin Miller points to the fact that, in New Zealand, “the Government’s main focus at the moment is around warmer homes – heating and insulation. The message is muddled whether it is climate change or healthy homes and there is very little focus on how to decarbonise heritage buildings.”

Candy Chan concurs that, “global sustainability targets tend to be more focused on new buildings.”

Duncan Philips wonders, “How can we be expected to adapt older buildings to meet government targets, if those targets have not been designed with any heritage impact?”

To decarbonise heritage buildings, we will need to get creative…and cut back on the air conditioning

Candy Chan takes confidence from her experiences thus far.

“Hong Kong is promoting low carbon living in adaptive reuse projects; they purposefully do not install air conditioning. The buildings in the old days were designed to make use of the natural winds, have bigger windows to get natural light. If we can make use of these design features which are inherited in the building, we can help to reduce the energy consumption and reduce the reliance on air conditioning.”

Warren Adams echoes Ms Chan’s confidence. “Many of our older buildings were designed for the climate. If we restore them appropriately and introduce the elements that help to keep a building cool, then we can reduce usage of air conditioning. We also encourage people to utilise underused and vacant buildings. And we’re retrofitting buildings for operational efficiency and to encourage micro-generation of power in historic buildings.”

Robin Miller expands on the theme. “We could do a lot more to ask building owners to improve energy efficiency in their buildings.”

Duncan Philips, broadly in agreement with the other panellists, urges a shift in mindset. “I don’t understand why, in some sectors, there is this presumption that new build is better than what we already have. I don’t think that we need to decarbonise, we should be looking for better and more environmentally sensitive ways of generating energy.”