Lead times may have levelled out, but if you are commissioning the latest green technologies there could still be a bit of a wait. Brian Moone of Mace gives an idea of what to expect

The economic climate means that lead times are either falling or remaining static as suppliers, manufacturers and contractors compete to pick up the few projects available. Despite the economy, the sustainability agenda goes from strength to strength andthe impact it can have on lead times cannot be ignored.

Sustainability is measured by the environmental impact of the completed building and the sustainability of the construction process that built it. As most of the technology, processes and requirements relating to sustainability are still in their infancy, the availability of products may be limited, and this may lead to lead times being extended while specialist bespoke equipment is designed and made to order. Meanwhile, the construction process has to adhere to more onerous requirements governing the environmental, social and economic impact of projects.

As councils seek to achieve their environmental targets, developers are required to pay for more comprehensive and therefore more complex environmental solutions for their buildings. For example, one leading city developer was required to consider incorporating a biomass boiler in its office development to reduce its reliance on fossil fuels. The incorporation of a biomass boiler into a scheme extends the 8-12 week lead time for a standard boiler to 25-40 weeks.

Specialist equipment like this can also have an impact on the time allocated for commissioning. Project planners should also consider some of the associated equipment, for example for the delivery and handling of wood for fuelling the boiler as well as the removal of ash.

Another increasingly popular solution is the use of combined cooling, heat and power (CCHP) in the development. This captures and uses the heat generated in the production of electricity, which can bring energy savings of up to 40% and potentially reduce carbon dioxide emissions by up to a half. However, this specialist plant is generally designed and made for a specific project and with a small number of companies providing CCHP plant, the lead time can be as long as 60 weeks.

Nitrogen oxide (NOx) reduction for boilers is another area to be aware of. The lead time for this equipment is generally 15-20 weeks. Although this is likely to be procured at the same time as the other boiler plant it could extend the overall lead time by several weeks. It is important to consider the size of this equipment and its location. If plant is to be located in the basement it will be necessary to programme it in with the basement construction, which is likely to place it on the critical path of the project and therefore make the lead time more important.

The availability of most timber has now been stabilised, but some specialist timbers and veneers are still in limited supply

Alternative renewable energy sources such as photovoltaics or wind turbines on a commercial building may need lead times of 20-25 weeks to design and make the specialist equipment that can integrate them with the existing power supply.

The main environmental impact may be considered to come from systems that consume energy, but other more passive areas include the sourcing of FSC (Forest Stewardship Council) certified timber, which is certified as not contributing to global forest destruction. In 2007 the industry experienced a shortage of FSC timber as it struggled to cope with the increase in demand for environment-friendly wood. The availability of most timber has now been stabilised, but some specialist timbers and veneers are still in limited supply and in some cases there are restrictions on when it can be removed from the forest. These timbers take longer to source and as one joinery specialist explained, while in the past quality prime-grade specialist hardwoods could be sourced from the stock of a single supplier, it is now increasingly necessary to source from several of them. This can increase the sourcing process from two weeks to between four and six.

On projects that contain a significant amount of drylining it is possible for the contractor to procure bespoke board and metal studs to reduce the impact of off-cut waste. However, this requires a longer lead time to accommodate the design and the factory runs.

In addition to the sustainable design of the finished building, the contractor has to demonstrate that its construction processes are sustainable. It is important to consider, for example, deliveries to site. Suppliers are increasingly urged to maximise load sizes to minimise transport or to use consolidation centres. This requires an increase in lead times to ensure loads can be combined and materials and products delivered to the consolidation site to be held for a collective delivery as part of consolidated loads. Alternative transport such as rail and river or canal routes can also reduce carbon footprints. However, there is a greater need to allow more time for the delivery itself and for transferring it from the river, canal or rail track to the project location.

The wider impact of sustainability is largely a result of the new technologies and processes that require bespoke design and construction. As sustainable products and process become more commonplace, bespoke units will be replaced with standard components and lead times will reduce. In the interim, it is essential that careful consideration be given to the required lead times of any designs, systems or processes that require bespoke sustainable solutions.