Five detailed case studies in Section 3.4 cover the following types of buildings:
While the case studies concentrate on individual buildings, their analysis has been supported by the additional review of up to four other projects for each building type, where possible. More than 20 non-residential buildings in New Zealand have now adopted sustainable strategies to a lesser or greater extent.
It is difficult to draw definitive conclusions about the costs of sustainable buildings, as their nature and extent varies widely. It can also be difficult to differentiate between sustainable design and architectural features. Table 1 shows the indicative cost/benefits for the case study buildings. Some of the case study buildings have proved cheaper, others cost-neutral, and some more expensive. In forming our view on the value case for sustainable building we have therefore supplemented the case study data with overseas experience, where the extent and market for sustainable buildings is more developed.
The range of buildings illustrates that sustainable building strategies can be applied to any building type. The value case will, however, apply more to high intensity / long duration activities such as hospitals, than to low intensity / short duration activities such as schools. The nature of the building use may, however, make it harder to adopt certain sustainable strategies. Natural ventilation may have only limited application in hospitals, for instance, due to requirements for infection control, but can be widely adopted in other buildings such as schools. So although sustainable strategies can be applied to any building, their extent and value case differ significantly and require specific consideration.
The New Zealand case study buildings have all reduced energy and water usage (where conservation strategies have been implemented) compared to other buildings of the same type. However, predictions of energy used for the case study buildings have been generally optimistic compared to real data, generally because of extended hours of operation, inappropriate use of the building (particularly in the first year of operation), and factors that were not anticipated or interpreted correctly at the design stage.
The individual New Zealand case study buildings are almost all well liked by their users, as confirmed by both formal post-occupancy evaluations and anecdotal response. The sample is small and relates more to the better buildings, but New Zealand sustainable buildings generally have positive user satisfaction and potential benefits in terms of productivity, and are within the upper 5% of buildings surveyed by the Probe Study methodology (Leaman and Bordass, 2001). This may be largely due to the nature of the projects, with motivated clients and users, the relative simplicity / clarity of design intent of the sustainable strategies, and the interest, follow up and fine tuning of performance post-occupancy.
A number of the case study buildings faced an initial scepticism to adopting sustainable building strategies due to unfamiliarity, concerns about cost and performance and a lack of completed projects in the New Zealand context. In many instances, sustainable features were regarded as optional and were compromised - particularly when budgets were under pressure - even if they were not the cause of the situation. Sustainable features can be seen as soft targets for cost cutting - particularly for quantity surveyors and project managers.
The design and technologies employed in the case study buildings have generally proved reliable and fit for purpose. Any issues have been resolved during the first year of operation, as is normally the case for a conventional building. Some issues of summertime overheating in naturally ventilated buildings in the hotter and more humid Auckland environment could have been better addressed at the design stage - normally by a reduction in glass area or by better shading.
Most of the case study buildings are of a high architectural quality, as shown by the architectural awards they have received. This has undoubtedly added to the experience for all involved - client, design team and users. It has also added to the general user satisfaction of some of the case study buildings subject to post-occupancy evaluation. Combining sustainability and architectural excellence requires a much more involved, and therefore expensive, design process. Some of the perceived extra costs of sustainable buildings may be due to this combination.
Generally, the completed case study buildings may be considered state-of-the-art rather than leading edge, at least in an international context, and are therefore not highly innovative. The challenge has been to reinterpret some international approaches in terms of availability of materials and equipment within the constraints of the New Zealand construction market and cost envelope. Clients and design teams have been challenged to think harder and leaner to change the normal construction process and, in doing so, have unintentionally added to the sustainability of the overall solution in comparison to overseas buildings.
In all the case study buildings, clients have accepted the sustainable path. In hindsight, some would have gone further. The increased capital cost premium paid by some has quickly looked like a sound, far-sighted investment as energy costs have increased beyond expectation over the past 10 years. The statement is often made - "I wish we had done more".
Some general conclusions can be drawn from the case study buildings:
Sustainable buildings represent a viable and increasingly attractive alternative to conventional buildings with benefits in terms of operating costs, user satisfaction, future proofing and environmental protection.