Annual energy cost savings of £22,000 for award winning low carbon hotel

Following the implementation of Mabbett’s energy conserving and low carbon design advice for the refurbishment of Carnbooth House Hotel, the hotel has benefited from reduced energy running costs and minimising their carbon emissions.

Approach and Delivery

Mabbett were retained by the Carbon Trust to undertake an assessment of energy saving opportunities for Carnbooth House Hotel as part of a Low Carbon Building Design Advice Report and subsequent mechanical and electrical design of building services for refurbishment of Carnbooth House Hotel as a low carbon hotel.

From the outset this project presented a number of challenges, prior to the redevelopment, none of the building elements were insulated, this meant heat could readily escape through the large single glazed sash and case windows, roof, floors and solid stone walls. Furthermore, Carnbooth House, has a grade B listed status which meant any changes made to the building had to be appropriate and sympathetic to its character as a listed building.

To overcome the challenges noted above, Mabbett identified and designed the following energy efficiency solutions:

• Insulation: The external walls were insulated by installing rigid panels of insulation into a new internal timber frame internal to the walls allowing energy efficiency to be achieved without impacting the external appearance of the building. Furthermore, insulation was installed in the roof spaces and also below ground floor in several areas. Overall, insulation reduced building heat losses by ~60%.
  
• New Windows: New double glazed sash and case windows were installed which had the same appearance as the old windows. The new windows had a low-emissivity coating which allows sunlight to enter whilst inhibiting heat loss from the room. The window frames included closely fitting seals to provide draught proofing in the sliding sections. Overall, the new windows reduced heat losses by over 80% compared to the old units.
• Efficient Lighting: Energy efficient lighting was installed throughout the hotel, using mainly compact fluorescent lamps in table light fittings. In intermittently occupied areas such as public bathrooms, automatic occupancy sensors control the lights so that they only operate when the room is in use.
• New Gas Supply: Carnbooth House Hotel was not previously connected to the main natural gas supply and used an oil fired boiler. A new gas supply was installed as part of the development in order to provide fuel for catering equipment as well as lower carbon source of fuel for providing space and water heating. Natural gas produces ~20% less carbon than oil on a like for like basis.
• Gas Fired Condensing Boilers: Mabbett designed a new gas fired condensing boiler to maximise the efficiency of heat generation for the hotel. The new heating system was designed to complement the condensing boilers by using large radiators which operate at a lower temperature (than UK conventional heating systems) and so circulate reduced water temperatures back to the boilers – thus enabling them to run in condensing mode for most of the time.