British Land Retrofit Shows How To Decarbonise Heating

British Land's York House

When leading UK property development and investment company, British Land wanted to decarbonise its flagship London headquarters, the company took the opportunity to showcase how to achieve low carbon heating, without needing gas as backup.

York House is a five‑storey, multi‑tenanted office in Marylebone, previously heated by four gas boilers equating to over a megawatt of heating capacity. It also requires 24‑hour cooling with extended fresh air requirements. The new equipment is two Mitsubishi Electric i‑FX‑Q‑GO5 air source heat pump chillers with a combined heating capacity of 1,113 kilowatts and a combined cooling capacity of 1,250 kilowatts.

The Mitsubishi Electic Heat Pump Chiller installed

Working with the heat pump chillers is an EW‑HT/0612 water‑to‑water heat pump which raises the flow temperature from 50°C to 65°C, this means that the existing heat emitters could be left in place, saving both time and costs.

The project was part of British Land’s wider goal of achieving a 75% reduction in operational carbon and a 25% reduction in energy use by 2030, and the result is a building where heat pumps deliver a more than 400 kilowatt‑hour reduction in energy use year‑on‑year.

A corner view of York House

Matt Beales, Head of Technical Project Delivery at British Land, said, “The York House project is unique because it was the first building where we achieved full gas removal using heat pump technology. Our previous projects have retained gas, but with this one, we really wanted to lead by example as it's our head office.”

The design was provided by 21 Engineering, and the starting point was an advanced building model in line with the NABARS standard to identify what the actual peak load would be.

“We came up with the principle that we could utilise a 95% peak load to minimise the equipment size and optimise the project costs,” explained Phil Draper, Managing Director of 21 Engineering. “We looked at controlling the building on a demand‑driven strategy, which means that the building isn't allowed to get cold, and that reduces the time needed to heat it and maximises the efficiency of the heat pump technology.”

Two other main challenges then had to be addressed: The limited roof space and installing the new heating system in a fully operational building.

Schematic of York House Geoff Broughey, British Land’s Senior Technical Services Manager for York House, explained, “We decided to complete the works within normal office hours, so nearby apartments weren't disturbed, which meant the office building was fully occupied. Most of the work occurred on the roof, so the building occupants weren't aware.”

A structural survey of the rooftop was carried out because the footprint of the new equipment was slightly larger, and the weight also higher.

The roof space is very limited, so careful planning was needed with the installer, Nationwide Air Conditioning 3‑D modelling the pipework and surrounding areas to make sure there were no surprises.

The Mitsubishi Electric heat pump chillers are helping British Land to reuse waste heat from the process of heating the building and minimising energy consumption. The four‑pipe heat pumps use R513A, a refrigerant with a lower global warming potential (GWP), and this has helped British Land get the Energy Performance Certificate (EPC) rating for the building as high as possible.

Daniel Valente, Head of Projects for Nationwide Air Conditioning summarised the challenge. “The unique aspect of this project was that we had no hydronic separation and a much lower capacity on the water‑to‑water side so that we only injected the amount of heat required to give the building the load required during the winter months.

“The benefits to this were higher operational efficiencies, lower initial capital costs and a simpler installation.”

For more information visit: https://les.mitsubishielectric.co.uk/

You can watch a video on the decarbonisation of York House below:

Click the article to enlarge it.

British Land Retrofit Shows How To Decarbonise Heating