Featured image
Return to Newsroom
Mar 11 2022

New build or Retrofit?

Written by TCN

TCN transforms unloved buildings into surprising places that help businesses thrive.

Sustainability and reducing our carbon footprint is imperative to the protection of our planet and future generations. Avoiding unnecessary waste of natural resources in order to maintain an ecological balance should be at the forefront of decision-making in construction and property developments. Understanding the impact of our construction techniques can help inform our decision and ensure we’re doing the best we can for our future.

A great example today is this:

You have bought a site with a 40,000 sqft derelict building on it – it’s in a bit of a sorry state. It has great potential as a modern office building. 30% of it will need completely new construction, 10% may be salvaged.

In the UK, in 2022, developers pay a standard 20% tax on the retrofit of a building and 0% tax to flatten and build from scratch. There are not only costs to consider but also building heritage and historical significance, sustainability and future environmental impact too. What are your options? 

With a focus on Embodied Carbon you have two choices:

Option A whereby you demolish the existing and build a new office
Option B whereby you retrofit the existing building on site.

Option A: Construction of new building​ in CO2 emissions (Using an embodied carbon rate of 350kgCO2e/m2 (LETI 2030 targets for offices (conservative))

Module C1
3.4kgCO2e/m2 GIA
Total: 12.6 tCO2e (C1)

Transport to Landfill 
Assume 50km away
Module C2 0.005kgCO2e/kg waste
Total: 37.9tCO2

Modules C3, C4 0.013kgCO2e/kg waste
Total: 98.6tCO2

Grand total CO2 emissions: 1302 tCO2e

Option B: Retrofit CO2 emissions may be similar to: (Assuming retrofitting requires 10% of the building to be demolished and removed, and 30% new construction) 

10% Deconstruction & material
10% of total C1,C2,C3,C4 of other option
10% of (12.6+37.9+98.6)
10% of 149.1tCO2e
Total: 14.9tCO2e

30% new construction 
at 350kgCO2e/m2(A1-A5 New Building)
30% of 1302tCO2e

Grand total CO2 Emissions for Retrofit: 390.6 tCO2e


So, in terms of impact on the environment:

Option A – Demolish & Build New
1451 Tonnes of Carbon CO2
That’s the equivalent of cutting down 8707 trees 

Option B – Retrofit 
406 Tonnes of Carbon CO2
That’s the equivalent of cutting down 2433 trees

With a 36% reduction in CO2 emissions through retrofit processes, we want to encourage more companies to look for new ways to deconstruct and re-use. There are many specialist Engineering Consultants such as Buro Happold who can help investigate and integrate emerging technologies and energy systems that can further reduce a development’s impact on the environment.

Share this post