Our studio sits within Elizabeth House; we know a great deal about the building and so have used it as a case study to test out our approach to Retrofit in the city.
This site has been the subject of many attempts to redevelop. The main tower stands directly in between Westminster and St Pauls Cathedral, and over a complex network of tube lines. Our study investigated the potential to re-use the existing concrete frame of the buildings to create the backbone of a larger development. Our aim to double the net area and half the current energy use of the building (effectively quarter the energy used per m²).
As tenants we also wanted to remain in position whilst this all took place. With a team of engineers and cost consultants we developed a retrofit option that added 2.5 times the area to the site, had an option to maintain the tenancies in place and move them each once, and lifted the energy rating from an F to a B rating.
With larger more efficient floorplates the buildings net to gross area improved and the skin was designed to be adaptable to its orientation. The use of modern phase change materials in the façade enabled the building to capture the heat from the sun and emit it when the internal spaces required, thereby reducing further the buildings energy requirement.
The case study proved it was a viable alternative to new build based upon a modest rent of £35m² and a yield of 6%. As a model for the city we believe this approach fits well in today’s market where funding is tight, speculative development is high risk and the owners of property want to maximise their asset value, with a reduced planning risk.
The environmental argument is even more compelling, reducing the embodied energy, compared to new build that may take up to 60 years to repay, increasing the thermal mass of the building using phase change materials that are lightweight and upgrading the energy systems to provide new class A office space with a reduced energy use.
Our keen interest in Retrofit can be seen further in our Refurbishing London case study.
|Total build cost:||£180M|
|Total value @ £35m²:||£343M|