Table 1: Indicative cost/benefit summary for case study ecologically sustainable development (ESD) buildings
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| Building type |
Benchmark building capital cost |
ESD building capital cost |
ESD building premium (saving) |
ESD building premium (saving) |
Annual energy cost savings |
Annual water cost savings |
Total annual cost savings |
Simple payback |
20-year NPV for ESD measures |
|---|---|---|---|---|---|---|---|---|---|
Tertiary education |
2300 |
2000 |
-300 |
-15.0 |
6.3 |
0.0 |
6.3 |
N/A |
-338 |
Hospital |
2400 |
2435 |
35 |
1.5 |
9.5 |
1.0 |
10.5 |
3.33 |
-72 |
Secondary school |
2430 |
2570 |
140 |
5.7 |
7.5 |
0.6 |
8.1 |
17.3 |
41 |
Library |
2384 |
2494 |
110 |
4.9 |
7.5 |
0.0 |
7.5 |
14.67 |
32 |
Office - low/ medium ESD |
2000 |
2130 |
120 |
6.0 |
11.0 |
0.3 |
11.3 |
10.65 |
-3 |
Office -medium/ high ESD |
2000 |
2230 |
230 |
11.5 |
17.0 |
0.6 |
17.6 |
13.09 |
-23 |
Average |
2252 |
2310 |
56 |
2.43 |
9.80 |
0.42 |
N/A |
N/A |
N/A |
Median |
2342 |
2333 |
115 |
5.30 |
8.50 |
0.45 |
N/A |
N/A |
N/A |
Notes:
1. Discount rate of 8.5%
2. Energy and water costs assumed to increase at 3% above inflation.
3. Three-year pre-design and construction period, with 20-year consideration period.
4. Costs have been normalised to 2005.
5. The library case study includes a number of materials features which add significantly to the sustainability of the building but which do not have a direct payback to the building owner. These include certified timber, alternative to CCA and LOSP timber treatment, recycled wool acoustic insulation, ceiling tiles with 70% recycled content, plant systems endorsed under the environmental choice labelling scheme, modular carpets with 100% recycled face fibre, cement with 70% fly ash content, crushed demolition materials as hardcore, alternatives to PVC and on-site waste management. These measures were generally included within a 1% premium on top of the construction cost.
6. Alternative on-site stormwater management systems such as swales and rain gardens can generally be achieved for little or no cost premium provided the budget includes a reasonable allowance for landscaping. The hospital case study included a stormwater retention pond which attracted a relatively significant cost premium.
We conclude that the purely sustainable features of a building add around 2-6% to the cost, compared with a conventional building. As discussed elsewhere in this report, operating cost savings pay this back many times over during the life of the building. This compares to international data as follows:
- Australia 2-4%
- United Kingdom 10%
- United States 0.7-6.5%
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