The challenges and issues faced when updating heating systems in listed buildings

Listed properties come in a vast range of shapes and sizes from small industrial workers cottages to castles, churches and cathedrals. One thing they all have in common is that they are often difficult to heat.

When it comes to heating listed buildings you often hear tales of woe - draught, cold and malfunctioning heating systems are par for the course. The task of making historic buildings cosy, snug, warm and energy efficient is a huge challenge.

Many listed property owners accept this as a downside of owning an older property and put off heating renovations for this reason. However, in many cases old heating systems become unrepairable and replacing the heating system becomes a necessity.

But with building restrictions to contend with it isn’t as straightforward as replacing a heating system in a modern home. Let’s take a look at some of the challenges and issues when updating heating systems in listed properties.

Most modern heating systems are designed for buildings which have a different relationship between heat and moisture than older buildings. Traditionally constructed older buildings were built to be heated one room at a time and heat up and cool down more slowly.

Understanding the relationship between airflow, heat and moisture in older properties is essential when completing any renovation work, especially when selecting a replacement heating solution. It is vital that considerations for maintaining a comfortable indoor environment are balanced with preserving the structure of the building.

We have become accustomed to elevated comfort thresholds, but modern heating solutions are often inappropriate for a historical environment. Badly chosen heating options can cause preservation problems.

There are various options to consider when upgrading the heating in historic properties. While gas central heating is the best option (it can be cheaper than electricity), many listed buildings are off the gas grid.

Air source and ground source heat pumps are very popular options and for larger rural properties biomass boilers are another choice - though disadvantages include having space to store fuel, and also the fact that biomass boilers can be bulky and require regular maintenance.

Hot water systems are generally a good option, but installation of new pipes in buildings can be problematic when it comes to building preservation. No alterations are permitted to the internal layout without listed building planning permission, which require that any modern services installed have to blend sympathetically with the period features of the property.

Zehnder’s Charleston electric, oil filled radiators, for example, are energy efficient, adaptable to the construction situation, offer a high level of heat capacity and are classically styled - making them perfect for old buildings.

Electric storage heating and underfloor heating can also provide additional background heat when the building is in use.

Historic buildings benefit from a stable environment, so heating that causes large temperature fluctuations isn’t advisable as this will exacerbate condensation.

Limiting the disturbance to the fabric of any listed building is a major priority when installing a new heating system, but how easy the system is to install is often overlooked.

A different approach is often required when installing a brand new heating system in an old building compared to a new one. For example, any cabling or pipework may not be able to take the shortest or most direct route so as to minimise damage to the building structure or specific features of interest.

Destructive chasing (cutting a groove into a surface to install pipes) should be avoided. Using existing mouldings or balustrades to hide pipe work and cables or routing them under floors or above ceilings is a better option where possible.

It is important that radiators or heat emitters fit into the building without being obtrusive to its original structure and architecture.

Zehnder’s Charleston radiators with their robust design and timeless, elegant aesthetic were selected to upgrade failing old heating systems in a number of churches, including St Peter’s RC Cathedral in Lancaster, St Joseph’s Church in Skerton, St Paul’s Church in Scotforth and St Mary of the Angels church at Bolton-Le-Sands.

The radiators were chosen because they complied with the requirements of the buildings’ listed status and did not detract from the historic interiors. The heat emitters also offered a high level of heat capacity and energy efficiency which made them well-suited to the tall church buildings.

Heating older properties efficiently is difficult. Historic buildings often have insufficient insulation. Historic homes adviser, Robert Lloyd-Sweet, says a lot of energy waste in old buildings is due to overdue maintenance.

Heating in old buildings is often wasted when the building is draughty, so a ‘whole building approach’ to achieve energy efficiency is recommended. See more in Historic England’s guide on How to Improve Energy Efficiency.

Upgrading building elements such as roofing, walls and floors and renovating windows to make them less draughty are further steps that can be taken. Even the simplest common sense things can make a difference such as opting for thicker curtains and carpets, and fitting draught excluders to letterboxes, windows and doors.

Refurbishing sash windows and adding loft insulation will also help to improve thermal capacity. Consider using a lower-carbon energy supplier.