Sustainability and green certification

In fact, it is difficult to design a building using IWBDP without incorporating sustainable features. The reverse is also true as acknowledged by Reed (2006) who states that an integrated design process is required for the success and cost-effectiveness of a green design. In a conventional process green features are often considered after the initial design has been formed which can be disruptive to the design process and also more costly, as noted by the US Department of Energy (2001).

This process often includes integrating green design strategies into conventional design criteria for building form, function, performance and cost. If a building is designed as usual green technologies are usually applied as an after-thought and this results in poor integration into the overall building design objectives and the greening strategies are more expensive to implement.

Using IWBDP on a sustainable project allow green features to be included in the very first stages of the design process. By engaging an environmentally sustainable design (ESD) engineer at the beginning of a project, green design opportunities can be identified and incorporated into the initial design. Energy, thermal and daylighting modelling should be carried out during the early stages of the process to allow optimisation of the design by determining:

• orientation and location of the building
• shape of the building
• internal layout of the building
• amount and type of glazing
• thermal performance of the building envelope
• shading features
• presence of thermal mass
• heating, cooling and ventilation system.

Most of these factors are locked down within the initial stages of the design. In a conventional design approach, modelling is either excluded completely or, if included, carried out during the developed design stage and so provides limited benefit to the project other than design verification. Energy and thermal modelling can be used to make the building more comfortable for the occupants, improve energy efficiency and reduce HVAC system requirements or improve passive heating, cooling and ventilation design. Daylighting analysis can also help to improve the amount of natural light available to internal spaces and reduce the requirement for electrical lighting. These investigations are crucial to the design of a green building and usually also play a part in the green rating and certification of the design. Currently, the only official green certification scheme available in New Zealand is the NZGBC Green Star for office design. This rating tool assesses the sustainability of the design based on these eight criteria:

• management
• indoor environmental quality
• energy
• transport
• water
• materials
• land use and ecology
• emissions.

The assessment of these criteria is combined to produce one score which can then be compared to:

• 4 Star, which signifies ‘Best Practise’
• 5 Star, which signifies ‘New Zealand Excellence’
• 6 Star, which signifies ‘World Leader’.