By Ross Ellis Stewart, Principal Architect at Ross Ellis Stewart Architect
With the IPCC report this week heralding a future where carbon emissions must radically change or the threat of the catastrophic events of global warming will rain down on us, the spotlight turns on our existing, fossil fuel era architecture and how we can bring it in line with a net-zero carbon future.
When we took our first look around the dilapidated wreck of the former J&W Campbell & Co garment factory in Glasgow’s Merchant City, it seemed as though the years of neglect would negate any attempt to rediscover the original character and vibrancy of the building in its heyday let alone do so in a way that would allow it to function as a 21st century workplace.
So how can owners of listed buildings not just get them ready for a net zero-carbon future but let them stand as shining beacons for change?
At The Garment Factory, we found a building that was merely sleeping and were able to peel back the bedclothes to shine the light of day on this gem of a building once more. This meant stripping out a century’s worth of internal modifications to reveal the original layout and fabric of the building. What’s more, revealing and understanding the original construction of the building allowed us to make interventions that worked with the original fabric to deliver our sustainability aims.
Natural stone is getting a lot of press right now due to its low carbon credentials, but existing buildings are often already made from stone and it’s already on site!
At The Garment Factory we carefully restored the building’s red sandstone facades to ensure that they were coping correctly with moisture and would withstand another hundred years of use. On the inside, original lime plaster was retained as much as possible due to its excellent hygroscopic nature which allows airborne moisture to pass through and vent to the outside through the lime mortar of the façade. Where the lime plaster was missing due to damage or later alterations a substitute plaster called Limelite was used which mimics the breathability of lime plaster but is much easier to apply. Breathable paints were also used to the internal faces of the external walls to ensure that breathability was maintained improving indoor air quality.
There may come a time when we have to bite the bullet and insulate the external envelopes of our traditional and listed building stock and this presents its own challenges. Not just the exterior appearance of a building is listed as the interior of a listed building is also protected. Adding thick layers of insulation to the outside of facades would obviously adversely affect the appearance of our listed buildings but so too would it affect the listing if it is applied internally. Furthermore, adding insulation to traditional buildings is not so simple as it may seem. Problems with condensation within the stone and timber construction of traditional buildings can cause them to deteriorate if appropriate airtightness and vapour control is not achieved. It is possible to insulate our traditional buildings but it takes skill and care.
At the Garment Factory we chose not to insulate the walls but rather use the thermal mass of the thick stone like a storage heater. This would store heat energy when the building was heated and radiate it back into the interior at other times. This also created a natural cooling effect in summer by absorbing heat during the day and releasing it at night. We did however super-insulate the roof of the building as there have long been products available to insulate roofs and mitigate any condensation risk plus, heat rises. We also upgraded the extensive roof glazing to maintain good provision of natural light while mitigating heat loss.
Outdated and inefficient building services can contribute massively to a building’s in-use carbon emissions, at The Garment Factory we retrofitted a full new set of building services ensuring improved energy efficiency to lighting with all LED bulbs, water usage with low-flow fittings, heating through new A+ rated gas boilers (although admittedly these are still fossil fuel burning but hybrid systems with gas boilers linked to air and ground source heat pumps are becoming more common). The biggest departure from the standard servicing model for a CAT A office refurbishment was to eschew air conditioning in favour of assisted natural stack ventilation. The boffins at Breathing Buildings, an offshoot from the University of Cambridge, have a range of solutions for buildings where the plan is too deep for openable windows to give enough ventilation to maintain healthy indoor air quality. At the Garment Factory we utilised their low energy fans at roof level and dropped ventilation stacks down through the building to each of the office floors. CO2 sensors within the offices linked to a traffic light system tell the occupants when it’s time to crack open a window. If the warm stale air in the vertical stacks is moving a bit too slowly, the fans on the roof kick in to give it a helping hand.
I’m massively proud of what we achieved at The Garment Factory but it is just the start of what is possible with our existing building stock. If we are talking about embodied carbon, it makes sense to reuse existing buildings as much as possible rather than waste their embodied carbon and generate more through demolition and new construction. Further innovation and training in how to get these fantastic buildings ready for their new low carbon lives is going to be essential if we are to preserve them while preserving the planet and ourselves.