Underfloor heating
UFH goes green T
Chris Jackson from Uponor discusses the underfloor heating specification for the new GSK Carbon Neutral Laboratories for Sustainable Chemistry at the University of Nottingham
he first thing that strikes you when you see the new GSK Laboratories for Sustainable Chemistry at the University of Nottingham’s Jubilee Campus is that it is a strikingly different building, with its timber facades, curved ventilation towers and sloping green roofs. The pleasing aesthetics of FDG Architects’ design are far from the only stand out features of this project, however. In fact, it’s the combination of a highly thermally efficient building fabric and a building services specification based on renewable energy sources that have helped to earn the £15.8 million building its status as a carbon neutral development.
Not only has the building achieved a BREEAM ‘Outstanding’ rating for its energy efficiency, putting it into the top 1-2 per cent of buildings, it has also been accredited as a LEED ‘Platinum’ development with an EPC A+ rating. Powered and heated by solar and biofuel energy (with a gas-fired boiler installed for use only as an emergency back-up), the building has been designed to be carbon neutral over its 25-year lifespan and to offset 100 tonnes of carbon per year with the excess energy it feeds back into the grid – enough to pay back the carbon used during the construction phase.
Reduced embedded carbon
Part-funded by GSK, the new facility provides 4,500m2
of teaching and research space. Delivered
by main contractor, Morgan Sindall, with building services designed by Aecom and installed by Imtech, the project not only considered the energy performance of the building fabric and services, but also the embedded carbon of every aspect of the specification. For the heating system, there was never any question that underfloor heating would provide the best option as a solution that is both compatible with the lower heat inputs of renewable energy sources and capable of adjustable heat outputs to manage comfort temperature levels within a highly thermally-efficient building. When it came to the choice of underfloor heating system, however, the reduced embedded carbon of the Uponor system and the ability of the Uponor team to work with Morgan Sindall on
buildability considerations were both pivotal to the specification. As a manufacturer, we were able to supply accurate data on the carbon used during manufacture and transportation of the underfloor heating system as part of the clients’ focus on calculating the environmental values of the scheme.
In slab installation
The building’s biofuel CHP unit provides its main heat energy source, generating 193kW of heat alongside 200kW of electrical power, which supplements the 200,000kW/h/annum of energy from the solar PV installation. Using an undisclosed sustainable liquid biofuel, the CHP feeds a thermal store and the underfloor heating. The underfloor heating system has been installed at both ground and first floor level but the Uponor team worked with Morgan Sindall from the early stages of design development to adapt the original approach, thereby achieving time, cost and carbon savings. The initial specification for the ground floor was for the underfloor heating pipework to be laid in the screed. Changing this to an in-slab specification enabled the project team to further reduce the embedded carbon of the scheme by removing the materials required for the screed and exploiting the thermal conductivity inherent in the concrete slab to deliver a more efficient installation. The 20mm diameter Uponor Q&E PEX pipework was looped into position in a zoned configuration and attached to the steel reinforcement rebar for the slab prior to the concrete pour. Held in place by pipe tie wires, the robust Q&E PEX pipe will outlast the service life of the building. Moreover, installation within
the jointless floor slab will protect the pipe from any risk of damage throughout its lifespan. Not only did the change of approach on the
ground floor reduce the materials required by removing the screed, it also speeded up installation, which took just two weeks. The system will also provide ongoing maintenance benefits, with only the manifolds installed above ground level requiring any maintenance.
CLT deck
The first floor construction was a cross laminated timber (CLT) deck, which required a different approach for the underfloor heating system. Once again, the Uponor team worked closely with Morgan Sindall to optimise the specification in line with the project’s aims of reducing embedded carbon and material consumption. The Q&E PEX pipe diameter was reduced from 20mm to 16mm and this was installed in pre- routed insulation boards on the CLT substrate, along with the heat emission plates. The completed zoned loops of pipework were then sealed in place with a board overlay, prior to the installation of the building’s floor finishes.
The change in pipe diameter was facilitated by the wide range of pipe sizes within the standard Uponor range and a collaborative approach to finding the most cost- and carbon-efficient specification to achieve the required heat outputs.
Pioneering scheme
Uponor provided design, supply, installation and contract management of the underfloor heating requirements at the GSK Carbon Neutral Laboratories for Sustainable Chemistry, which has now been completed to a positive reception from students, staff and the design and construction community. Underfloor heating is just one of the elements that have combined to achieve the project’s carbon neutral goals and the installation demonstrates both the value of the renewables- friendly technology and the importance of embedded carbon data in securing specification on such pioneering schemes.
34 September 2017
www.heatingandventilating.net
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