Reducing energy consumption and the unintended consequences of energy efficient intervention in historic buildings

Background: Older historic buildings are often perceived as energy-hungry. The opposite is arguably the case. Until the Industrial Revolution, energy was expensive and difficult to exploit. Acceptable indoor air conditions had to be delivered with little or no input from "building services" such as heating. Instead, massive walls and floors provided thermal buffering from exterior conditions; barriers such as timber panelling prevented them drawing out the body heat of occupants.
These and many other comfort and energy-saving features - and the knowledge underpinning them - were largely lost as centralised energy supplies encouraged the development of building services such as space heating and cooling. The introduction of thermometers completed a shift away from building users' understanding of complex sources of discomfort towards an emphasis on air temperature.
The energy- and carbon-saving measures currently promoted for the built environment centre on air temperature, cutting the loss of conditioned air by reducing ventilation and increasing insulation of the building envelope. These retrofits can have serious negative impacts on traditionally constructed "greatcoat" buildings, which depend on very different materials and systems to control moisture from those used in modern "raincoat" construction. Maladaptation can lead to failure of the building fabric, increased use of energy and carbon, and serious comfort and health issues.
Air temperature is an easy parameter to measure, but - as recent research has demonstrated - comfort and discomfort are considerably more subtle. This project aims to broaden our understanding of the causes of thermal discomfort, investigate innovative ways of assessing it, and quantify the benefits (for the user, the building fabric, and the environment) of traditional approaches to remediation.

Aims
- summarise the unintended consequences associated with current thermal-comfort criteria
- identify the specific factors that most influence thermal discomfort in historic buildings
- develop innovative methodologies for quantifying building user discomfort
- quantify the benefits of these methodologies for energy and carbon reduction in historic buildings, including the avoidance of unintended consequences for the building fabric.

Research hypotheses
1: Parameters including air movement (draughtiness), relative humidity, ambient humidity, conductive and radiant body heat loss, and user activity play a much more important role in thermal comfort and discomfort than air temperature.
2: Traditional ways of managing thermal discomfort can significantly reduce the pressure on air heating and cooling systems, allowing a reduction in energy and carbon use without negative impacts on building usability or historic building fabric.
3: Robust ways of assessing and dealing with the real causes of thermal discomfort could help achieve important through-life reductions in the consumption of energy and carbon in buildings.