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M&E challenges on a listed London retrofit

Consulting engineering company Crofton Design worked with the Portman Estate to reduce the carbon output of one of the estate’s Georgian residential properties in London.

The Portman Estate is made up of 110 acres of land in Marylebone, and has buildings dating back to the 16th century.

This project, 21-22 Montague Street, is intended to act as a test bed for Crofton to try a series of technologies and ideas, monitor the building and assess how best to achieve maximum carbon reduction across the portfolio of 700 residential properties.

Many of the properties are Grade II-listed, so one of the requirements was that the outward appearance of the buildings remained unchanged.

Greenest solution targeted

“We were challenged by the Portman Estate to come up with a solution that would provide the greatest carbon reduction in the buildings,” Crofton director Steve Hale explains.

“We looked at a series of options and decided to use a mini district heating system, solar thermal panels on the roof and a micro CHP system.”

Crofton installed a three-tier heating system, designed to ensure only the exact amount of heat needed is generated. The solar thermal panels provide a portion of the hot water for the buildings through a thermal storage system. This is topped up by the micro CHP that also feeds into the thermal store.

The third component is a conventional boiler that kicks into action if the other two sources are not sufficient in the cooler months.

“Space was a big challenge because there was not much available for plant,” Mr Hale says. “We had to use the old coal vaults below the pavement, and this meant some plant would not be accessible without deconstruction.

“So we worked with Portman Estate’s FM team to organise the plant and identify which kit would not need regular maintenance and placed it in areas that would only be reached when the whole system is taken apart.”

Although this would mean dismantling part of the system in around 20 years, the team were confident this will be relatively easy and that this was still the best option.

Guinea pig project requires monitoring

As this project is intended to act as a test case, its performance will be closely monitored by both Crofton and the Portman Estate.

“We had a high level of input as this was quite a complex series of instillations, and we also worked with the residents after the refurbishment was complete to make sure they understood how to use the building in the most energy-efficient way,” Mr Hale says.

The monitoring will confirm if the retrofit has been successful, and what impact user behaviour has on the projected energy savings. The Portman Estate will then decide what measures to implement across the whole estate.

Other measures used on this project include:

  • All rooms have heat exchanges extracting heat from the thermal store or central plant;
  • Parts of the building fabric were rebuilt to improve U-Values and thermal performance, while windows at the front of the property were double glazed;
  • LED lighting was installed throughout the property.

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