Show preview: Innovations for the Built Environment

As clients increasingly address energy efficiency measures through the use of sustainable materials as a matter of course, the focus is starting to shift onto what other measures can be taken. This year, there is likely to be a greater emphasis on resource demand in product manufacture, contributing to the 'carbon footprint' of a development, as well as the environmental impact of the project as a whole.

A trend that is growing in momentum is the demand for green roofs - vegetated roofs - to replace the natural environment lost due to a development. In particular, local authorities are demanding green roofs to be included in the specification for hospitals, schools, social housing and commercial buildings, both on new build and refurbishment projects. Indeed many city councils now require a building over a certain size to feature a portion of green roof.

At this year's Innovations for the Built Environment exhibition (Earls Court, 26-28 February) - which includes Ecobuild, Futurebuild and Cityscape - more manufacturers than ever will be present to push the benefits of green roofs. Laying down the case for green roofs alongside them will be Dusty Gedge, a long-time campaigner, who will be detailing their advantages and opportunities as part of the show's seminar programme.

Gedge's campaign began in order to encourage wildlife, principally the black redstart population, back into inner city areas. Now, green roofs are being used to attract black redstarts and to help address other nature conservation issues throughout London and the UK.

But according to Phil Singleton, green roof product manager at Icopal, the major driving factors for the specification of green roofs are now sustainable urban drainage and insulation. "Green roofs can dramatically reduce heat gain in a building. They act as a good insulator when they're dry, but are less efficient when wet so it's not an alternative to insulation, just and addition," he explains. "Also, as they have a deep substrate, rainwater is withheld and released over a longer period of time, reducing the likelihood of flooding."

This position is confirmed by Patrick Faramia, export manager at FDT, who says the dramatic floods of last year have highlighted the drainage benefits of green roofs. "The UK is known for its rainy days, but it's used to steady rain. When you experience dry weather followed by storms, water runs of urban areas quickly and causes floods. Green roofs will absorb some of this rainwater and reduce the risks," he adds. And as the substrate releases the rainwater it will also help filter it, removing heavy metal pollutants.

Energy savings

While it is accepted that a green roof will cost more than a conventional solution, the saving in terms of a building's energy use can be considerable. In countries where green roofs are more established, payback periods have reportedly been as low as two to three years, depending on a building's location.

Brad Bamfield, managing director of The Solution Organisation (also speaking at Ecobuild in a seminar entitled 'Understanding Whole-life Costing for Renewables') is adamant that green roofs are the most cost-effective and worthwhile of all environmental technologies. "If you think of all other environmental technology they involve heavy industry," he says. "Green roofs can be made from completely recycled material, don't cost much to do - in some cases nothing - and can save a considerable amount of energy."

On brownfield sites, it is even possible to use excavated material on the roof of a development, saving on transport and disposal costs. But to take this approach, a sympathetic roofing membrane manufacturer needs to be found as this practice would invalidate the warranty on the majority of products.

Bamfield explains there is even conjecture that green roofs could provide a cure for sick building syndrome. "If the theory is correct, sick building syndrome may be caused by roofs exposed to high temperatures, which in turn heat other building materials, releasing chemicals that are circulated by the air conditioning. The reduction in heat gain facilitated by a green roof would prevent this from occurring."

As with any flora and fauna, green roofs need regular maintenance whether they are the extensive (sedum-based), intensive (a variety of plants) or brown roofs (recycled aggregate left to colonise naturally). "The big difference over a normal roof is that you have to specify, install and maintain a living environment," continues Faramia. "The issue is not so much the matting or drainage, it's how the green material is sustained."

This means that clients must include long-term maintenance contracts as part of the tender. But as biodiversity becomes more widely specified it is unlikely contractors will need to turn to Alan Titchmarsh. Most membrane manufacturers work with partners that will lay and maintain the vegetation, but it is important to establish who is ultimately accountable.

Faramia adds: "The main contractor or developer must consider the maintenance. Is the roofing contractor able to do this? Assessing the guttering and waterproofing is one thing, but who is responsible for the vegetation and what happens when a hot summer affects the growth on the roof?"

The issue of maintenance will clearly have a marked impact on cost, as will the green roof type and choice of plants. "Each job will vary in terms of cost," continues Singleton. "So it is important to establish early on the exact design required to get an accurate picture."

However, once the growing pains have been resolved, a green roof will provide a low cost and minimal maintenance energy saving addition to any building. As Bamfield says: "A large building with ground source heat pumps and a green roof will tick all the environmental boxes, make the setting much more pleasant for the occupants and attract a premium for the property."

Essential components of a green roof

Timber frame: to hold the roof elements onto the roof. In some cases extra supports may be needed to ensure the building can take the load.

Root membrane: a damp proof membrane.

Filter sheet: this stops fine material from leaving the roof. It is generally a sheet similar to those placed under patios to keep weeds out.

Moisture blanket: a woolly fleece that holds water, usually referred to as a geotextile membrane.

Substrate: the medium on which the plants will grow, consisting of aggregates such as crushed concrete/brick, limestone chippings, gravel or clay pellets. Above it should be another layer consisting of sand or soil.

Plants: the species selected will depend on the substrate and the substrate depth. They can be seeded or plug planted.

CJ looks at some of the latest products that will be on show at Innovations for the Built Environment

As part of the Road to Zero Carbon feature at Futurebuild, H+H Celcon will be exhibiting its range of aircrete blocks, including its thin-joint and flooring system. Ian Excall, head of marketing at H+H, said that as aircrete is largely manufactured from recycled materials and has good thermal insulation properties, it meets the demands of the sustainability agenda. The company's Ra House, an approach to housebuilding which involves a team of specialist contractors quickly installing the shell of a house, will also be on show.

Solarcentury aims to demonstrate how developers and housebuilders can reduce the carbon emissions of their projects using building-integrated solar photovoltaic technology. Resembling standard roof tiles - and installed in the same way - 8m2 of its C21e solar electric tiles can generate 850kWh of electricity per year. The company says a standard three-bedroom house is capable of generating 2,500kWh of electricity per year, equivalent to a saving of 1.5t of CO2. When used in combination with the C21t tile, the products can deliver up to 60% of a three-bed home's hot water requirements and half of its electricity needs.

A new design concept is to be launched by Yorkon at Ecobuild in order to demonstrate the design flexibility of its steel-framed modular building system. The designs are particularly suited to retail, leisure and commercial schemes. The concept involves modules with 12m clear internal spans for buildings up to six-storeys high. It suggests a six-storey linear building sitting alongside a curved building around a central plaza and featuring elements such as external terraces, glazed atria and vertical light shafts.

Kingspan Off-site will be exhibiting its portfolio of building systems that, it claims, can meet any level of the Code for Sustainable Homes. In addition to its TEK building system, which was employed for the level six development at the BRE last year, its Optima and Kingframe systems will be on show, together with a range of steel and timber façade systems.

 

 

 

 

Among the rainwater systems Marley Plumbing and Drainage will feature at Ecobuild is Waterloc, a modular stormwater storage cell. Constructed from columns of honeycomb cell extrusion made from recycled polypropylene, the product is designed to replicate natural drainage patterns. It will stall the progress of rainwater, controlling run-off and helping prevent flooding downstream.