HOLYROOD has ambitiously committed Scotland to becoming a net zero society by 2045, so given around 40% of current carbon emissions come from buildings, modernising them is paramount.

Creating brand-new greener structures is one thing, but by far the bigger challenge is that 80% of buildings that will exist in 2045 are already here. Everything from our cherished Victorian tenements to beautiful old schools and landmark public buildings will need to undergo significant upgrades to fit into our new net zero society.

Unless urgent action is taken now, hitting that daunting deadline is a pipe dream.

The Government estimates the total cost of converting our buildings to zero emissions – often referred to as "retrofitting" – as £33 billion, which is likely to have massive implications for all.

Inevitably, homeowners will shoulder some of these costs, whether they’re compelled by legislation to adapt their homes, or through increased taxes.

It’s not all bad news, though, as these upgrades could see huge energy bills become a thing of the past.

You may be familiar with Passivhaus, an ultra-low energy approach to new building design. The equivalent standard for old buildings is EnerPHit. Passivhaus or EnerPHit homes often don’t need heated even on the coldest days, and there’s less risk of condensation or mould. As the cost of living crisis bites, most of us would give our right arms for these snug homes of the future.

Decarbonisation throws up a host of practical and potentially expensive challenges for public buildings. For example, if a local authority needs to retrofit a school, where do the pupils go in the meantime?

One forward-thinking council asked us to examine how it can decarbonise all its primary schools, of varying age and construction. We’ve used computer modelling to estimate space heating requirements before and after installing wall and floor insulation. We also worked out how four classrooms at a time can be retrofitted, so schools don’t need to close during works and multiple schools can be upgraded simultaneously.

Public sector organisations should look now at how to decarbonise their estates as a whole, to save time and money when compared to taking a one-building-at-a-time approach.

There’s also the challenge of maintaining the appearance of historic buildings. Nobody wants to see beautiful exteriors covered with insulation, but there are ways around this. We are working on the conversion of a sandstone villa in a conservation area to a nursery, increasing energy efficiency using internal insulation only.

We’ve also worked on a retrofit project where Historic England understandably didn’t want the windows changed for aesthetic reasons – so we replaced single panes with specialist "vacuum glass" inserted into existing frames, keeping appearances the same, but dramatically reducing heat loss.

Yes, this mammoth task is daunting. But we should rise to the challenge, as we must reduce energy demand, not just for our planet but also to reduce fuel poverty and improve the comfort and wellbeing of every building user.

We may not have all the answers yet, but we must learn and innovate quickly, so we can ultimately reap the long-term benefits.

James Gemmell is a sustainability and retrofit expert at Holmes Miller architects