Oxley Conservation Heritage Appraisal

Low Energy Victorian House 17 St Augustine’s Road

Heritage Appraisal

High energy use and comfort levels are a relatively modern phenomenon and many traditional buildings were constructed at a time when far less energy was consumed. There is a great deal of synergy between the conservation of the historic environment and the need to reduce the demand for energy, but also potential conflict.  

The Low Energy Victorian House project offered the opportunity to learn how to get the balance of building and energy conservation in an actual building. The occasional event in the life of a building, a major refurbishment, gave the chance to find out what is achievable in terms of reducing the fossil fuel usage of a traditional residential dwelling located in a conservation area.

 Conservation Areas are designated under The Planning (Listed Buildings and Conservation Areas) Act 1990 as areas of special architectural or historic interest, the character or appearance of which it is desirable to preserve or enhance.  In a conservation area, the main emphasis is on external appearance, with surface materials (walls and roofs) and the details of windows, doors, and rooflights being considered important.  Historic buildings vary greatly in the extent to which they can accommodate change without losing their special interest. Some are sensitive to the slightest alteration, especially externally, or where they have important interiors, fixtures, fittings or other detailing. Others may already have changed significantly during their lifetime and can accommodate further change relatively comfortably.  A historic building in its townscape or landscape setting, together with its interior decoration, fixtures and fittings, can be regarded as a composite work and a document of history. Principles of good heritage conservation value retention rather than replacement and upgrading in benign ways.  When contemplating work to historic and traditional buildings, a reasonable balance needs to be struck between the opportunities for future-proofing the building and making energy and carbon savings, alongside the principles of heritage conservation and technical risks associated with changes to the building fabric.  The need to respect traditional buildings is widely recognised, even amongst groups pressing for urgent measures to improve the energy efficiency of the building stock. 

Government policy is to improve the energy efficiency of buildings and reduce the associated greenhouse gas emissions. This includes tightening building regulations, most recently in April 2006 for England and Wales. A major change has been to expand the requirements for work to existing buildings, including historic and traditional buildings. The building regulations themselves state general Requirements only. They are supported by Approved Documents (ADs), which set technical guidelines on what is regarded to be a reasonable response to these Requirements in modern construction where there are no other constraints. The ADs make clear that historic buildings warrant special attention and compliance with their targets may not be appropriate. In some historic buildings a “reasonable response” to a regulatory Requirement may be no change at all. In others whilst some parts should definitely not be altered, elsewhere there may be good opportunities though the standards, methods and materials suggested in the ADs may not be appropriate. Exceeding the requirement in one area (e.g. equipment efficiency) may help compensate for shortfalls elsewhere (e.g. insulation levels). In historic buildings, usually it is the fabric-related demand-reducing measures that create the greatest conflicts between heritage and energy conservation. For example, the historic, aesthetic and cultural interest of the external and internal surfaces of a wall, or the detailing around the windows, may make wall insulation completely impossible. And where it is aesthetically acceptable, it may introduce technical risks, often moisture-related, that preclude this measure. However, in the same building it might be relatively easy, cost-effective and technically acceptable to improve the airtightness of the doors and windows, insulate the roof space, install a more efficient boiler, controls and electrical equipment and change to lower-carbon fuel supplies. From the heritage conservation perspective, opportunities to improve energy performance and reduce carbon dioxide emissions need to enhance and not conflict with the conservation of the building.

At 17 St Augustine’s Road, the first stage in assessing the heritage value of the building was to evaluate the elements that make up the special character and interest of the building, including:

• External features such as a decorative façade, roof details, windows and doors
• Internal spaces and layout the interior plan of a building is one of its most important characteristics and should be respected
• Internal features of interest such as decorated plaster surfaces, panelling, floors, window shutters, doors and doorcases
• Details such as mouldings, stucco-work, wall and ceiling decorations can be just as valuable in simple vernacular and functional buildings as in grander architecture, and can be a building’s most important feature.

What was identified to be significance about 17 St Augustine’s Road was the unaltered state of the building since its construction over 150 years ago. Very few internal alterations had been made to the fabric of the building, making the majority of the elements and finishes contemporary with the construction of the building. Interior features such as timber shutters to the principal windows are intact and fully operational. Only the basement had been the subject of alterations and replacement of original elements when converted into a single dwelling during the 20th century and subsequently of no significance.

The lack of intervention extends to the floorboards which are all original from the ground floor upwards. Most of the boards had never been lifted and even when the central heating was installed, the level of disturbance was kept to a minimum by locating the radiators close to the rising pipework. Careful removal of the paintwork also revealed that the interior had only been limited to a number of internal decorative schemes.

The level and the quality of the internal finishes are the significant feature of a London residential dwelling of this age.

In terms of the refurbishment works, from the heritage perspective the quality of the existing internal condition of the house informed the approach to be adopted, appreciating and reflecting its individual history and character. In this unique situation, the apposite approach is to design the refurbishment works to be appropriate and compatible with the historic fabric that causes the minimum amount of intervention.

Oxley Conservation made a review of the options for improving the thermal performance of 17 St Augustine’s Road, balancing heritage and energy conservation. The report setting out the issues encountered from the heritage and energy conservation view when pursuing the different options for demand-reducing measures of each element, was prepared  for the client to develop their approach to implementation of achieving reductions in use of fossil fuels in the refurbished building.