Building Performance

Building Performance in use

To date no systematic analysis of building performance, energy consumption or greenhouse gas emissions has been able to be carried out. This is primarily because the heating and cooling system has not yet been formally commissioned, so it is not certain whether it is operating exactly as designed. 'As installed' documentation and operational manual are to be supplied to the University, followed by testing and witnessing. Once this happens, the important issue to study will be the extent to which gas back-up is drawn on to supplement the heat generated by the solar collectors. The gas boosting cuts in automatically when the temperature falls below a certain point - exactly where this point is set is obviously crucial to energy consumption, and there is a view that it is currently set somewhat higher than necessary.

Electricity consumption data is available for the office complex, and it is possible to use this to do a partial comparison with a current benchmark for office buildings. The benchmark to be used is from Building Owners and Managers Association, Energy Guidelines (1994), using their 'typical design target for (low energy) offices' for Canberra, taken as the location nearest to Thurgoona.

In the following comparison, space and water heating have been left out altogether because of the unavailability of reliable data for Thurgoona.

Annual Electricity Consumption By End Use (space and water heating excluded) MJ/m3/yr

The reason that the School of Environmental and Information Sciences uses 35% less electricity than the benchmark's are the absence of lifts, the absence of an electricity-driven cooling system and probably a lower lighting demand due to daylighting. Office equipment electricity consumption could be assumed to be the same as the benchmark.

When energy performance data for Thurgoona becomes available, how that data is used comparatively will be crucial. The general tendency in benchmark comparisons is to compare like with like, office buildings with office buildings, air to air heat pump systems with air to air heat pump systems, and so on. This approach may work well for building managers, who are faced with the task of trying to operate an existing system more efficiently. But it can be misleading for building designers, in that such 'fair' comparisons can obscure the significant differences in energy consumption between different systems.

Thurgoona's hydronic system is unique, so what should it be compared to? Hydronic heating systems that circulate hot water through floor slabs are not uncommon (more so in the northern hemisphere), but these are generally gas rather than solar powered. There are even fewer hydronic systems that are configured to contribute to summer cooling, and would any of these use renewable energy (windmill and solar) to pump cold water from a storage reservoir?

Comparative Costs

A conservative estimate of the capital costs of Thurgoona's buildings is that they are 4% above that of more conventional university buildings. A more generous estimate, taking into account savings on infrastructure, shows the cost to be 14% less. There are certain to be recurrent cost savings because of the way in which the facilities have been purpose-designed to reduce the uptake of mains power and town water.

Qualitative evaluation

An informal user evaluation was undertaken as part of this case study. Four small groups of building users were interviewed: students, administrative, academic and maintenance staff. A summary of their contents follows:

Thermal comfort in summer

Natural ventilation was viewed positively compared with the former air conditioned AWDC building, and the ability to open windows regarded as a distinct advantage. A staff member who kept a thermometer in his office and reported 28 as the highest summer temperature, which he felt was not good. It was noted that there was still some lack of understanding about how the building functioned, e.g., which elements were automatic and which manual, but this was seen as an issue of informal education. Some maintenance staff were sceptical about the potential of the hydronic cooling system to perform in a really hot summer, the School Building having experienced only one relatively mild summer.

Thermal comfort in winter

Differences within the building were less commented upon, the south side ground floor being the coldest. Students were less favourable about winter conditions. Administrative staff felt that it was generally comfortable enough, with it being reported that only two or three (of the 100) using supplementary heating in their offices during very cold periods.

Sound transmission

It was reported that because the natural ventilation strategy relies on keeping fanlights above office doors open, conversations can be overheard in the circulation spaces. One staff member said that she closed the fanlight when she wanted to have a private conversation, another said she had learnt to speak more quietly!

Lighting

Nearly all reported that artificial lighting was only required on overcast days. The building was visited on an overcast spring day, and in fact most offices did not have their lights on.

Composting toilets

Views varied, most liked the idea and had become used to them. Odour problems with toilets on the south side of the building were reported, which have since been rectified by altering the fan position.

What features do you particularly like?

This elicited very enthusiastic responses: "materials, energy system, fitout - the total concept"; "the timber and natural treatments"; "the earthy colours of walls, they're very easy on the eye", "the natural light and textures", "the composting toilets - makes me feel like I'm wasting water at home"; "best place I've ever worked", "an anti-stress environment", "I'd like my future home to be like this" (a student).

What features do you particularly dislike?

The only common response here was the complaint about sound transmission and difficulty of having private conversations. Other responses were more individualised: "access ramp is slippery when wet", "door movement when windy", "composting toilets are high maintenance", "landscaping is high maintenance because of hand weeding rather than insecticide control".

What was striking about talking to staff and students, was that their degree of satisfaction seemed to correlate very closely with the extent of their knowledge about the building. This is no accident, as staff were closely consulted during the design process, and some actively involved.