The Courts, Nottingham

Client Nottingham City Homes
Specifier Nottingham City Homes
Substrate Concrete Cross Wall Construction with Brick outer skin on the gable walls.
System PermaRock Mineral Fibre External Wall Insulation Systems
System 2
Finish PermaRock Silicone Ultra K & R Finishes
Finish 2 PermaRock Brick Slips
Project Overview:

British building contractor, Sustainable Building Services (UK) Ltd has completed an energy efficiency scheme that features Britain's largest battery storage facility for domestic energy, and the country's first low temperature district heating system. The work has been undertaken for Nottingham City Homes.

The £4 million project also entailed building new plant rooms, installing solar PV panels, and fitting solid wall insulation to four residential blocks.

Known collectively as "The Courts," the 5-storey properties are of concrete cross wall construction with brick outer skin on the gable walls. They are the subject of an ongoing European energy efficiency study. Accordingly, the work was partially funded by ReMo Urban, a EU-funded urban regeneration model. The work was procured through the Fusion 21 Retrofit Framework and SBS secured the contract in a competitive tender on the basis of price and quality submissions.

The project was conceived as an opportunity to test innovative energy supply and delivery mechanisms. To make this test viable, the properties first needed to be well insulated.

Energy efficiency improvements included fitting new insulation to walls, floors and roofs; replacing windows and some doors; installing low energy LED lighting; and remodelling private balcony areas. Solid wall insulation represented an important part of the whole scheme. In total, SBS installed external wall insulation to 94 flats and bedsits. The chosen system was a fire-safe mineral wool insulation system from PermaRock Products Ltd.

An important challenge was to address the risk of cold-bridging. The building features numerous walkways, balconies and soffits that would present a means for heat to be lost, but this was prevented through innovative detailing work. The building has several stepped levels and the designer of the external wall insulation system - PermaRock Products Ltd - developed detailing that accommodated these changes without leaving any areas exposed. Careful planning by key stakeholders meant that potential cold-bridging problems were eliminated efficiently and affordably.

Fire safety has been an important consideration. The system designed by PermaRock comprises fire-safe non-combustible mineral wool insulation, together with SiliconeUltra K render and a brick slip finish.

The finished EWI systems are supported by a 25 year guarantee from the Solid Wall Insulation Guarantee Agency (SWIGA).

The heat source for the low temperature district heating system was the return leg of an existing district heating system in a 270-flat block across the road. The initial heat is generated by a local energy-from-waste plant. This supplies the neighbouring tower at 90 to 100 degrees C, but the return leg supply comes in at approximately 70 degrees C. The feed passes through a new primary heat exchange unit, and then through domestic heat exchange units within The Courts. These replace existing gas fire boilers, so SBS has been able to remove gas entirely from the buildings.

The new scheme required the construction of a district heating plant room to serve the whole of The Courts, and individual electric plant rooms for each of the four blocks.

The scheme also entailed fitting solar PV arrays on all roofs, generating circa 91 kWp in all. To make the most effective use of this power, the properties are equipped with a new battery storage facility. This, like the PV model, is designed on a communal basis. It enables Nottingham City Homes (NCH) to buy electricity at the optimum times and to use grid balancing services to improve the model financially.

"This was a technically challenging scheme," notes SBS Project Director, Nigel Coxon. "It has involved some innovative technologies and approaches, and it has demanded effective partnership working throughout. However, we have an excellent relationship with Nottingham City Homes and we're very pleased by the results of this collaborative effort. The efficiency of the various systems will be scrutinised very carefully in the coming months and the findings will help inform a wider urban regeneration model. That will almost certainly include future strategies for energy efficiency and energy generation.

"One interesting finding that has already emerged is the success of the low temperature district heating system. The neighbouring district heating system is now heating many more properties than it did before, and without additional energy input. That represents a significant energy efficiency improvement. With all works now complete, the data will be studied by various partners, including Nottingham Trent University, and disseminated across Europe."

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