Mechanical and electrical strategies can dramatically influence a facility’s whole-life carbon. Whilst operational carbon from energy use is reducing as buildings become all electric, more energy efficient and the renewable energy percentage offered by the grid increases, this is far from the full picture.
The lifespan of MEP services and the type of system selected for an office building has a significant impact on whole-life embodied carbon. LETI highlights that MEP services account for 15% of embodied carbon in a new office but only have an economic lifespan of 15 to 25 years, so the real impact on total carbon footprint is much greater.
LETI predicts that ongoing maintenance and replacement accounts for 45% of whole-life embodied carbon and a sizeable proportion of this is related to MEP. As efficiency increases and operational energy reduces, the embodied carbon from construction, maintenance and replacement will account for two-thirds of a building’s lifecycle carbon.
The carbon impact of replacing MEP systems is not just a question of lifespan since retrofits and churn by tenants results in substantial alterations and waste. This cycle of occupation often sees systems replaced far in advance of their economic lifespan.
Our sustainability experts, led by Mark Terndrup, studied the embodied carbon associated with a variety of air-conditioning systems and then factored in the embodied carbon associated with typical fit-outs, maintenance, repair and replacement.
Discussing the findings, Mark said: “It is evident that Under-Floor Air Distribution (UFAD) systems are one answer to the challenge of energy efficient cooling whilst avoiding extensive whole-life carbon penalties. They have the least initial quantum of components installed and are far more favourable in carbon terms. UFAD means fewer physical components in the office space in comparison to alternatives like Fan Coil Units (FCU’s) and Chilled Beams.”
The ‘all-air’ UFAD cooling strategy works without ductwork or terminal units, cutting the number of components and materials. Instead, the raised floor is used as a supply plenum with adjustable diffusers set into the floor. This simplicity means that adaptation for cellularisation is straightforward, and maintenance is minimal. Alterations are limited to moving diffusers, lights and detectors, massively reducing equipment replacement over the building’s lifecycle.
UFAD systems can achieve free cooling for up to 85% of the year, reducing operational energy and working in harmony with mixed mode natural ventilation. The solution comes with a multitude of wellness benefits with better air quality, and occupants can have individual temperature control over their immediate area.
So why isn’t UFAD used more prevalently? The answer stems from the market perception that a solution so simple must be inferior. However, the ability for our buildings to respond to tenant needs without repeatedly making carbon intensive alterations is essential as we strive towards a Net Zero future. The simplicity of UFAD, with its minimal components, makes it easily adaptable to changes. Simplicity is key to unlocking the challenge of delivering low carbon strategies for our buildings, so we must convince the market that ‘Less’ is indeed ‘More’.
