The University is investing £3m in installations to enable more efficient and controlled heating and cooling in the Medical School and at Sutton Bonington campus. These combined projects will significantly reduce the University’s carbon emissions and current energy consumption, reducing costs in the long term.
Combined heat and power at Sutton Bonington
In space that previously housed Sutton Bonington’s incinerator, installation is underway of a combined heat and power (CHP) unit which will simultaneously produce heat and electricity for use at the campus. The £1.35m project can deliver around 40% of the site’s electrical and heating demand and is expected to be operational by November 2015 - there will be no interruption to heat supply throughout the autumn whilst the installation is being put in.
The scheme consists of two reciprocating engines converted to run on natural gas which drive a generator and can produce around 800kW of electricity and 970kW of heat to be used directly in our district heating system. The CHP unit is estimated to reduce annual energy bills by £260,000 and carbon emissions by 1,150 tonnes of carbon dioxide.
Cooling the Medical School
The Medical School is a highly regulated and energy-intensive building, with annual energy consumption more than double that of Jubilee Campus. Most of the building’s comfort cooling is provided by a chilled water system, part of which is served by 40-year old steam absorption chillers. The system chills water to 6°C at fairly low efficiencies, so the unit cost of delivered chilled water and the associated carbon emissions are relatively high, and contribute to the Medical School being the largest single building energy user across Nottingham’s UK campuses.
This winter we are installing two more high efficiency cooling units, at a cost of £1.23m, to provide more reliable and efficient cooling. They’ll provide chilled water to meet approximately 75% of the Medical School’s chilled water demand, completing the work started in summer 2014 to install the first cooling unit. The chillers are electrically powered and utilise high efficiency compressors with magnetic bearings and inverter-driven motors to minimise energy input. These measures, along with improved chiller controls, are expected to reduce annual energy bills by £220,000 and carbon emissions by 790 tonnes of carbon dioxide.
The project is scheduled to complete by the end of February 2016 – ready for the start of the main cooling season.
Reducing temperature extremes in the Medical School
Elsewhere in the Medical School, the University is investing £400,000 to reduce the temperature extremes experienced on B and C floors, following on from a successful project on floors D and E in spring 2014. Building users will benefit from a warmer building in winter and a cooler building during the summer, with the changes also reducing the University’s carbon footprint.
The construction of the building, with large voids between each floor and uninsulated floor and ceiling slabs, means that there is considerable heat transfer to and from the voids during the year. Each service void has 95 open louvres, which are intended to avoid excessively high temperatures during the summer. However, the louvres are fixed open and such uncontrollable ventilation means winter temperatures can drop to 8°C, whilst summer temperatures can still exceed 30°C during calm weather conditions.
Starting in early autumn 2015, the project will install fans, dampers and Building Management System controls to provide controlled ventilation to 190 open louvred vents in service voids B and C. This will significantly reduce the heat loss from the user floors into the voids during winter and reduce heat gain from the voids during summer. Reducing heat loss during very cold weather conditions will have the added benefit of being able to heat certain ‘hard to reach’ rooms to a suitable temperature without resorting to supplementary heaters or overheating other parts of the building.
Temperature monitoring and subsequent calculations have identified potential annual savings of £79,000 and 274 tonnes of carbon dioxide.
Posted on Friday 28th August 2015