By: Sarah Peterson, Director, Energy & Sustainability, Harley Haddow
For existing and heritage buildings the journey towards Net Zero emissions can seem complex. It doesn’t need to be.
It’s widely been acknowledged that this decade needs to be one of climate action. Without taking drastic steps now, the Net Zero carbon target set for 2050 will not be achieved.
When it comes to the infrastructure of our towns and cities, we can’t build our way to Net Zero, we also need to address the impact of existing buildings. What then? 80%* of current buildings will still be around in 2050, and with the energy consumption of these accounting for around 40%** of the UK’s annual carbon emissions, successful decarbonisation of existing assets will be essential, as will a new approach to managing these buildings.
Every journey starts with a single step
The UK has set carbon reduction targets – with the UK targeting net zero by 2050 and Scotland aiming for five years earlier. Many local authorities, organisations and public bodies also believe they could be ‘Net Zero-ready’ by 2030.
Into a new landscape
An essential part of any Net Zero carbon strategy is limiting the amount of energy buildings need to run. With buildings, this relates to operational carbon related to the energy used to run them – so heating, lighting, hot water plus any energy used for plug-in equipment.
There’s also whole life carbon which looks at the materials used to build with and calculates the total embodied carbon, including the carbon used to manufacture and transport the material. This element is not currently included in legislation for buildings but will be gradually considered for new buildings. Existing buildings will have low embodied carbon already as the building is being re-used.
The route ahead
For existing and heritage buildings there is little or no published guidance on Net Zero demand targets, something we think is urgently needed.
Heritage listed buildings are some of the hardest to improve for a Net Zero future and despite the challenges of the pandemic, most people will still occupy, operate, or own an existing building.
While getting existing buildings to Net Zero is challenging, it also gives the greatest potential savings. Stakeholders in existing buildings should not be asking whether to get on the Net Zero journey, but how far and fast to go.
As well as setting building energy demand targets, the other essential requirement is to stop using gas as a fuel. The electrical grid is decarbonising – so we’re moving away from gas and coal fired power stations and onto renewables.
If electricity is your primary fuel supply in coming years, you’ll become Net Zero by default. But while electricity is undoubtedly greener, it’s not cheaper, currently coming in at five times the cost of gas per kWh, although with an uncertain gas supply network this cost difference may start to shift.
It calls into questions whether hydrogen could be one of the Net Zero solutions. While there’s been a lot of hype there needs to be a serious revolution in the way it’s produced with the majority currently made from natural gas or coal. The best solution is to reduce energy demand first, and then provide an efficient electric heating system.
Best way forward
Data and digital twin modelling can reveal a treasure of information. At Harley Haddow we create a digital twin model of the building using dynamic simulation software and compare this with measured utility consumption. This helps us understand where and how energy is used and if the building management systems are working as efficiently as possible.
A digital twin model gives an accurate baseline to measure and test options on, with the following steps:
- A hierarchy multi-level approach is used to see what savings can be made, eg can the building’s fabric be improved to reduce heating demand.
- Reduce demand by looking at the building’s management systems eg can lighting be improved.
- One of the most important steps is the replacement of the gas heating (normally from a heat pump to ground, water, air) which reduces the carbon further and limits running costs.
These steps can be carried out in a phased and tailored approach and will set your building on its journey to Net Zero. From the start of the project, your carbon impact will continue to reduce alongside the implementation of each step.
A final view
Net Zero can seem overwhelming, but it’s totally achievable. While every business has a role to play in tackling climate change, it also makes commercial sense with benefits including reduced costs, enhanced reputation, competitive advantage and investor confidence.