Retrospective UoN: A more scientific approach to thermal comfort and natural lighting

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This is an excerpt from Philip Pollard’s PHD thesis, concerning the design and construction of the Callaghan campus of the University of Newcastle (UoN) between 1990 and 2005. This section deals with the nursing faculty, including the issue of striking the right balance between airconditioning and other heating and cooling solutions – which remains an important topic today.

The Nursing building was to be an extension connecting the existing Hunter Building to the Richardson Wing, which had been poorly designed with subterranean rooms and dust ingress from a nearby unsealed road. The brief included the opportunity to refurbish the Richardson Wing to address the worst of its shortcomings. 

Three design proposals were received, and as per the previous competitions, the senior academic members of the PAC constituted the majority of the jury, with the Dean of Architecture and the Built Environment and PPE also having a vote each.

Ultimately a unanimous decision was made in favour of the Stutchbury/EJE partnership’s design.

This design was based on two narrow wings, each allowing good cross ventilation and topped by a “fly” roof. Between these wings, the 450-seat lecture theatre was located on the natural slope.

The roof of the theatre was slung between the outer walls of the two wings. The trusses for the theatre roof had a horizontal top chord, with a curved bottom chord – rather like an inverted Sydney harbour bridge. This generated a great ‘belly’ shape on the underside forming the ceiling of the theatre, which was clad in a beautiful pine ply. Walls were lined with recycled hardwood planking.

The design abandoned the existing two subterranean classrooms of the Richardson Wing, which became a car park, and included the construction of a new entry courtyard accessed from the northern corner of the new building. 

The architects had obtained some preliminary advice during the competition phase from a specialist environmental engineering consultancy, Advanced Environmental Concepts (AEC) led by Ché Wall, and as part of the commissioning of consultants, AEC were retained to model the thermal performance of the new building, and to advise on the improvement of the existing Richardson Wing’s thermal performance.

Advice was also obtained from specialist architect Rod Simpson on embodied energy in materials and potential for off-gassing of fittings, finishes and furnishings on the interior.

The design development phase of the project was a stimulating time, as collaborations threw up a raft of opportunities.

The academic members of the PAC consulted with their fellow academic and non-academic staff colleagues and students about design refinements. These ideas were brought back to the PAC group where they were used to inform the discussion.

At the same time, physical planning and estates specialists, including Mim Woodland (landscape and stormwater management), David Alexander (energy and potable water) and I, explored with our commissioned design consultants a range of opportunities for achieving as vibrant and sustainable project as we possibly could.

The newly acquired capacity to accurately model both natural light conditions within spaces, and the effectiveness of sun shading was a significant contribution to the process, as was the capacity to undertake modelling of air movement and temperature within spaces.

This gave a good indication of the comfort levels that could be achieved within office and tutorial spaces – which was especially important because under the UoN adopted policy, airconditioning was not provided in these spaces.

A reverse brick construction was adopted, which exposed the thermal mass of the brickwork to the interior of the rooms, outside of which was a layer of high-performance insulation, a vapour barrier and the corrugated zinc-alum exterior cladding.

Under the UoN adopted policy, airconditioning was not provided in these spaces

The building’s columns were of in-situ concrete which was also exposed for its thermal mass, as was the underside of the coffered pre-cast concrete floors.

The “fly” roof of the wings of the building served several functions. Firstly, it provided a useful and attractive space for recreational activities and group gatherings, secondly (and most importantly) it shaded the concrete roof slab of the offices, and thirdly it was angled so as to direct the desirable north-eastern breezes into the courtyards – thus overcoming the problems that arose with internal courtyards in the Hunter building that became excessively hot and airless in some conditions.

The building made extensive use of light shelves and used a range of means for introducing natural light deep into the building. These included using obscure glass “portholes” set into the corridor floor of the upper floors, which allowed filtered daylight to reach the lower corridor.

The airconditioning design for the theatre was possibly the most innovative component of the thermal comfort design aspects. AEC proposed using a geo-thermal heat pump either in place of, or to augment, the airconditioning system used in the theatre.

This technology had been used successfully in north America in cold areas, but had not previously been used in a large scale application in Australia. A feasibility study was undertaken to determine the financial viability of the system, and it was revealed that either as a stand-alone system, or as an augmentation to an efficient refrigerated airconditioning installation, the cost of the geothermal component would be repaid well within its operational life.

Given the fact that the geothermal component replaced the need for a cooling tower, there were further savings in not having to continually maintain and sterilise water in this component. As part of the study, indoor temperature predictions were made for the geothermal system applied on its own, which would have produced a minimum temperature of around 16 degrees Celsius on the coldest day, and around 28 degrees Celsius on the hottest day.

These temperatures represented a remarkable improvement on the ambient temperature even at the extremes, however, given the fact that the space to be conditioned was a theatre – in which people have pre-determined comfort expectations – we decided that the geothermal system should be used to augment a conventional (but efficient) reverse cycle plant.

A test well with a 300 mm diameter was drilled some 100 m (300 ft) into the rock, confirming that the site was suitable for the application, and that the year-round temperature deep in the earth was 19 degrees Celsius.

The geothermal component has now more than paid for itself and continues to give trouble free service.

Calculations were undertaken to determine that a field of 48 wells, spaced in a grid 3 m apart (4 rows of 12) would be sufficient for the application. The system used was a closed one, using welded polypropylene tube which looked quite like black irrigation pipe, with each well having a loop of two pipes running its length.

The hole was back filled with bentonite clay, which is a good thermal conductor. Water was pumped using a single small pump around the closed system and, irrespective of the outdoor temperature, returned to the plant room at the predicted 19 degrees Celsius.

The water in the closed system was then fed into a heat exchanger with the chilled water (reverse cycle) airconditioning system, which supplied air via an underfloor plenum in the theatre. Only that part of the theatre occupied by people (the part up to approximately 2.5 m above floor level) needed to be maintained at optimal temperature – above this, hot air rose, collecting waste heat from the light fittings en route, and was exhausted through a series of slots in the ceiling to be returned to the plant room.

When completed the conventional part of the system needed some minor tweaking as part of the commissioning process as it was rather too cold in summer. Once this commissioning was completed, the system consistently performed extremely well, and achieved outstanding energy consumption figures. The geothermal component has now more than paid for itself and continues to give trouble free service.

The senior academic members of the project advisory committee reported that the Nursing building was generally well received by the building users.

The theatre was the space most popularly requested by faculties when timetables were established at the start of each semester, but an ongoing criticism arose from occupants of some of the offices, who would have much preferred airconditioning to be provided – however this was not a decision of the design team or the PAC, but rather a requirement of the airconditioning policy.

The theatre, its foyer and ancillary spaces often were used as the venue for conferences and other functions. The theatre’s acoustics worked well both for the unamplified voice and for electronic audio, and in spite of having a fairly large capacity of 450 seats, the space felt remarkably intimate.

A wall of fixed glazing in the theatre was provided which can give the occupants of the space a glimpse of the bushland outside when the room lighting does not have to be dimmed for image projection. The operation of the metal blackout louvres was undertaken automatically by the touch screen audio visual system (AMX).

The courtyard spaces of the Nursing building and the upgraded Richardson Wing provided a variety of informal outdoor uses including seating and an often-used bank of stairs which provided a casual sitting area which could at times function as useful “third spaces”.

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