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Cost effectiveness of Green Roofs

 

Commercial Roofing: Can Green roofs be more cost effective?

The recent climate change demonstrations gather pace as young adults have followed school children onto the streets to demonstrate against government’s lack of action.

Construction accounts for 10% of emissions so it won’t be long until Greta Thunberg starts pointing her finger at us. What are we doing to reduce omissions and improve the environment?

During the day plants absorb CO2 and omit oxygen thus improving the air quality. The planted areas of a green roof also help to filter impurities from rainwater which falls on them thus improving water quality. This benefit is greatest where the planting materials is deeper.

Hot roof tops have been shown to create an updraft which carries particles into the atmosphere. Green roofs help to reduce roof top heat. Studies in Germany saw a differential of 10-20,000 particles per litre to 3,000 particles per litre near buildings with green roofs.

During periods of heavy rainfall surface water drainage systems can come under pressure due to the speed at which rainwater is diverted into them in urban environments. This can often cause flooding and recently in London we have seen events where surface water has spilled into the foul water system forcing sewage into the River Thames. Green roofs absorb large quantities of rainwater, filtering the remainder through the planting and water retention systems. The surface water run-off from a green roof is thus much reduced.

Because of the predominance of dark surfaces, concrete and tarmac, urban areas are typically up to 4 degrees Celsius warmer than surrounding rural areas. This creates what is known as the heat island effect. Warmer environments create a greater need the use of air conditioning creating more greenhouse gasses. Green roofs also offer cooler and more welcoming environments for insects and wildlife passing through urban areas.

Finally the additional planting and growing materials which make up a green roof improve the thermal performance of the building. This not only reduces heating costs and by reducing the need to heat and cool the building, it also improve the performance of the roof waterproofing system, making it last longer and reducing the number of times it has to be renewed over the buildings life.

At Maguire Brothers 95% of the waste we produce is recycled and all our vehicles are hybrid. We encourage our clients to make choices which have a lower carbon footprint, most of which give a reasonably quick return on investment.

Clients are less willing to invest in longer term investment choices. However it’s our job to inform as to how doing so, can actually be more cost effective in both the medium and long term.

To find out more about sustainable roofing projects, or any commercial roofing needs our surveyors are always on hand to share over 40 years’ worth of knowledge.