Reducing embodied carbon through smarter material choices

OceanView4U, Radharc na Chaoláire, Furbo, Co. Galway

A small development of passive houses built for the private rental market overlooks Galway’s Atlantic Coast, Radharc na Chaoláire.

These houses feature low carbon concrete as part of a considered approach to high-performance, low-impact building — fittingly for a project designed by RIAI sustainability taskforce chair Helena McElmeel.

Aided by structural engineer John Britton, the design team also made efforts to reduce the embodied carbon of concrete used onsite.

50% GGBS from Ecocem was used in poured concrete from Coshla Quarries, including the raft foundation. The scheme, which offers uninterrupted views over Galway Bay, with the Burren and the hills of Clare in the distance, has intimate ties to its Gaeltacht location — including its name.

Radharc is the Irish word for view, but the meaning of Chaoláire may be lost to people outside of Connemara. It means ‘narrowing of the bay’, and references the name that generations of local seafarers have used for the stretch of water which the houses overlook.

The schemes ties to the region’s heritage go far beyond a name. McElmeel, whose ability to fuse location, sustainability and cutting edge design has given her a well-earned reputation as one of the leading architects in the west, embraced the resources in the area. Not only does the scheme tip its hat to the local architectural vernacular but McElmeel adopted construction methods based on local skills and local material supply chains: cavity wall construction on a 150mm concrete raft foundation, built with 50% GGBS.

At times the conversation around carbon in buildings can split into two camps — with some advocating reducing carbon emissions from energy use across a building’s life, while others argue that as the electricity grid decarbonises and people switch to electric heating, the focus should shift to materials.

For architects like McElmeel, it’s not a binary choice. A long-standing certified passive house designer, McElmeel has delivered a number of buildings to the passive house standard, in the process virtually eliminating the need for space heating while delivering constant comfort and fresh air.

But McElmeel is also committed to tackling embodied carbon too. That’s why, in addition to specifying 50% Ecocem GGBS in all poured concrete on site, McElmeel specified insulation made of up to 75% recycled glass.

Schemes like Radharc na Chaoláire point at an architect who is seriously grappling with whole life carbon and ensuring that ambitious efforts to reduce energy demand, and improve home comfort, can go hand in hand with efforts to reduce embodied carbon.