Heating, Cooling and Ventilation
Daylighting, Sun Control and Artificial Lighting
Sustainable Materials and Labour
Taking it further: the Lecture Theatre's energy system
Site Planning (back to top of page)
The requirements of water harvesting, cleansing and storage dominate the design of the site, which is marked by wetlands and retention basins towards the north boundary and storage dams on the highest central point. The local authority required that stormwater and treated grey water not be mixed, which meant dedicating considerably more of the site to water storage and treatment, than if they had been allowed to mix.
Existing drainage patterns and the requirements of the water management system were used to define the placement of buildings, with roads, paths and services following site contours. Precincts have been planned on a pedestrianized scale to avoid the need for car use. While this might seem like nothing more than common sense, it doesn't always prevail. There are a number of educational institutions built on rural and semi-rural sites around Australia, in which buildings and precincts are spaced widely apart, necessitating the use of cars to move around the campus.
Building Form (back to top of page)
The environmental program has largely determined the form and appearance of the buildings. The rammed earth walls ranging in thickness from 300-600mm (chosen for their high thermal mass) give the buildings a solid, heavy appearance. Thermal chimneys, which double as skylights are also visually prominent.
Water self-sufficiency is declared visually by the incorporation of rainwater tanks into the building structures - 43 in all across the campus. Continuing the water theme, the heating and cooling of the buildings is by a hydronic system that circulates hot or cold water through floor and ceiling slabs, a spray mist cooling system is used in the in the Student Pavilion courtyard, while a small waterfall creates spray mist to pre-cool the air entering the Lecture Theatre.
Looking more closely at the the offices of the School of Environmental and Information Sciences, it is clear that early design decisions favoured a passive approach to heating, cooling, ventilation and lighting. The idea was to make the building fabric do a good deal of the work of providing thermal (and visual) comfort, which involved:
- building orientation (long north-south aspect)
- construction materials (rammed earth walls, concrete floors and ceilings)
- windows (predominantly on north and south facades)
- floorplates (narrow, to maximise light penetration)
Exterior view of School of Environmental and Information Sciences Building
Building Planning (back to top of page)
Being a new campus, the building program has been staged. The Student Pavilion was constructed first and used as a prototype to test the rammed earth construction and the mixed mode system that combines natural ventilation, solar-driven hydronic heating and evaporative mist cooling. After completion in 1996 and having gained the University's confidence that the new systems were effective, the School of Environmental and Information Sciences, herbarium, specialist teaching building and IT hub followed, then four student residential cottages. The most recent construction, opened in February 2000 is the Teaching Complex and Lecture Theatre and a further two cottages in 2002.
Pre-design Strategies (back to top of page)
Architect Marci Webster-Mannison, who had spent four years doing applied research in ecologically sustainable building before taking up the post of Design Director at Charles Sturt University, recognised the opportunity that the largely unserviced site presented for the creation of a very low impact, environmentally high performing campus. The University Council supported the idea, adopting a set of environmental principles for the new campus, which were then translated into seven sustainability objectives:
1. Water resources (conservation and efficiency)
2. Vegetation (protection and regeneration)
3. Soil (protection and conservation)
4. Animal populations (protection and conservation)
5. The working environment (healthy, high quality)
6. Energy Conservation
7. Responsible resource use
Design Strategies (back to top of page)
A multi-discipline design team was assembled early in the project, including specialists in fields as diverse as wetland design and thermal modeling. The passive and active systems were developed collaboratively, and the key elements were assessed using heat / airflow and daylight computer modeling.
Two years of planning and design went into the School of Environmental and Information Sciences Building, in which the University's adopted sustainability principles were translated into design concepts. Members of the School of Environmental Sciences have had a major input into the design of the building and grounds, most notably, Dr. David Mitchell's role as wetland designer.
The designers consulted closely with staff who were to occupy the new buildings. This resulted in some significant design changes in response to user priorities. For example, the layout of the herbarium was organised according to the work flow, so as to minimise the need to use toxic insecticides to protect plant specimens. Specimens are brought in from outside and over a period of time move through a series of air locked cleaning rooms. To date chemical control has not been necessary. Here, the benefits of a chemical-free workplace were regarded as worth the trade-off of having to air condition some of the space.
Ongoing involvement of staff in the design process and pre-occupancy briefings were very important in gaining support for the vision of an ecologically exemplary campus as well as in familiarising future occupants with less familiar technologies.
The University's own construction department was responsible for procurement, dividing the construction tasks into a series of work packages, rather than letting a single contract. This was a good decision as it made it possible for the designers to respond to suggested modifications from contractors (which they frequently accepted with enthusiasm), but without compromising the guiding intent. Local tradespeople were favoured.
Heating, Cooling and Ventilation (back to top of page)
For heating and cooling a mixed mode system which favours passive techniques has been taken. The passive elements of the School of Environmental and Information Sciences Building are:
- building orientation (long north-south aspect)
- high thermal mass materials (rammed earth and concrete)
- window placement (predominantly on north and south facades)
- sun shading
- natural ventilation
- automated night purging
-wool insulation in ceiling cavity
The rammed earth walls are unreinforced, forming the structural walls and columns throughout the building, and thus defining the spaces even down to the individual offices, going against the standard practice of lightweight internal walls such as plasterboard. Floors and ceiling slabs are concrete, with ribbed profile ceilings to increase surface area. This means the building has a great deal of thermal mass, which acts to stabilise indoor temperatures. Wall thicknesses have been calculated for an optimal 12 hour lag.
The stack effect is used to assist cross ventilation and summer cooling, the key element being thermal chimneys. Night purging, through automatically operating low and high level louvre vents flushes the internal spaces of hot air, expelling it through thermal chimneys, lowering the temperature of the thermal mass.
The main active element is the hydronic system which circulates water through floor and ceiling slabs for supplementary heating and cooling. It is controlled by a BMS (building management system) and triggered by in-slab temperature sensors. Concrete tanks located in the in ceiling of each building store hot or cold water for use in a closed loop system via thermal exchange. In winter, roof mounted solar collectors heat the water, with back-up from a gas boiler when required. In summer the system works in reverse, dissipating heat through the solar collectors at night with further cooling by thermal exchange with water pumped up from the reservoirs to the top supply dams (pump is wind-driven with photo-voltaic back-up).
Additional thermal comfort is provided by ceiling fans in the offices.
While the BMS controls the slab heating and cooling system as well as the opening and closing of louvres for night cooling, all offices have openable windows, allowing occupant control. A number of windows may be used sub-optimally without affecting overall comfort levels. Computational fluid dynamic modelling of the building assisted this aspect, and the passive design strategy more generally.
Crosssection
of School of Environment and Information Sciences
showing heating and cooling system
Daylighting, Sun Control and Artificial Lighting (back to top of page)
The strategy has been to reduce demand for artificial lighting through high levels of daylight and individual control. Effective daylighting has been achieved by the narrow floor plate (all work areas are less than 6m from windows), by fanlights above office doors and via thermal chimneys which double as skylights allowing daylight to penetrate the central interior spaces. Window sizes, roof overhangs and shade devices were calculated to allow maximum natural daylighting without glare and without compromising thermal performance.
Artificial light is really only needed on overcast days. It is provided by energy efficient fluorescent lamps (from 11 to 36 watts) with further efficiencies gained by only specifying 360 lux level at desktops, with other area lighting at 180 lux. The custom made lighting consists of standard fluorescent tubes fitted with curved perforated stainless steel covers that act as diffusers and provide up-lighting to the white painted ceilings. Lights are manually operated, except for those in store rooms and sanitary areas which are on timers and / or activated by photocell movement detectors.
Energy Sources and Renewables (back to top of page)
Mains electricity is used to supply lighting and general power needs. Extensive arrays of roof mounted solar collectors power the heating and cooling system (with gas back-up), while domestic hot water is supplied by separate roof mounted solar hot water systems (electric boosted). Both solar systems use gas boosting. Road and car park lighting is powered by stand alone photovoltaics, as is the back-up for the windmill-driven pump that moves water from the reservoirs to the top supply dams. The budget didn't stretch to photovoltaics for general power needs, but the roofs have been correctly angled and have sufficient space for later addition of photovoltaic panels.
Sustainable Materials and Labour (back to top of page)
Rigorous selection criteria were employed for materials selection, which favoured:
1. Low embodied energy
2. A high percentage of reused or recycled components and materials
3. Using low or nil off-gassing materials for a healthy indoor environment
4. Avoiding materials with high upstream impacts
This resulted in the following selections:
- recycled timber for windows, joinery and interior linings (MDF avoided because of manufacturing impacts and off-gassing).
- plantation softwood roof trusses and composite plywood beams (instead of native forest timbers)
- steel mesh rather than chemical treatment for subfloor termite protection
- paints and oils with low or nil volatile organic compounds (some of the paints were custom mixed, such as a non-titanium based white)
- linoleum floor coverings (lower manufacturing impacts than vinyl)
- wool ceiling insulation (less hazard risk in installation and removal than mineral fibre)
- polyethylene and terracotta pipes for drainage system (avoiding PVC because of its high manufacturing impacts)
School of Environmental and Information Sciences: Interior View showing internal void
These choices have contributed significantly to the character of the building. The variety of recycled timbers and different styles of joinery add richness and complexity throughout the school building. The commitment to materials reuse meant that the designers had to be responsive to what became available. This engendered a spirit of "creative opportunism", seen in the way in which steel shelving obtained from the dismantled stacks of the Dixon Library of the State Library of NSW, has been re-used throughout the offices, while the 25mm cast glass flooring from the same stacks has been strategically installed to admit light to lower levels and add visual variety to the upper level floors.
The policy of favouring local tradespeople is an important aspect of the project's commitment to sustainability. This is more complex than just local employment creation, as it involved inducting local labour into sustainable trades as well as providing experienced tradespeople with opportunities to innovate. An example of the former is the way in which the rammed earth construction proceeded. Earth on the site was not regarded as suitable unless rigorous quality control was exercised and this would only have been possible with a team of expert, non-local labour. Instead, material of a more consistent quality was sourced from a nearby brick quarry and the work proceeded using less experienced local labour overseen by the external rammed earth contractor. Thus skills in rammed earth construction have been gained locally.
Taking it further: the Lecture Theatre's energy system (back to top of page)
Each of Thurgoona's buildings has been informed by what was learnt from previous ones. In this respect the Lecture Theatre completed in February 2000 represents the most advanced stage of the energy system design. To appreciate this, we need to backtrack: in the initial design of the School building's hydronic system, summer cooling was intended to occur only by drawing on water from the reservoir. The contractor (Branco Boilers and Engineering of Albury) made the suggestion of also running the system in reverse to dissipate heat through the solar collectors at night when the air temperature is lower. So the system was modified to incorporate this, however as tank sizes and arrangement had not been specified with this in mind, the strategy could not be used to best advantage. When the lecture theatre was designed, this innovation was incorporated, using an optimally sized, dual tank configuration.
The lecture theatre presented the challenge of having to cater for large numbers of people in a confined space and having to respond more quickly to meet cooling requirements. Its construction is an earth covered concrete barrel vault, which acts to moderate heat losses and gains from extreme external air temperatures. It is naturally ventilated using the stack effect, with hot air from people, light and equipment being exhausted through louvres in a thermal chimney above the stage.
As in the School Building there is automated night purging to rid the building of unwanted heat and to induct external cool air. Fresh air enters through a plenum (which, in this case is a thermal labyrinth of staggered concrete blade walls supporting the seating tiers) and is distributed through vents along the tiers. A waterfall is located directly above the air intake louvres to the plenum which creates rainfall sized drops and spray mist for evaporative pre-cooling. The water is sourced from the rainwater tanks in the School and the Teaching Complex. Additional cooling is also provided by a geothermal exchange system of polyethylene pipes laid one metre under the ground.
Detail showing Lecture Theatre spray mist cooling system
Other Environmental Factors (back to top of page)
Water Management System (back to top of page)
Thurgoona's water management system is truly climate-responsive and conservation-oriented. Most of the region's 784mm annual rainfall occurs in winter and spring, meaning that getting sufficient water for the hot dry summers and autumn presents a problem. The principle adopted has been to harvest and store as much rain as possible and to recycle any water used on site.
The idea that water is a precious resource has informed the entire design of the Thurgoona campus. It is expressed visually, with rainwater tanks being structurally incorporated into the buildings, and even the cooling systems of the buildings are "plugged into" the elaborate, whole-of-site system that collects, cleanses, stores and re-uses water. Thus the energy and water systems are interdependent, an example of the relational thinking that has informed much of the design process.
Looking specifically at the water system: waterways and contour banks collect rainwater and direct it via grass swales down to wetlands for cleansing. This occurs through biological cleaning by plants and bacteria, clarification via sedimentation and further cleaning by aeration in which the water flows over rocks into in-stream treatment wetlands, then to three interconnected retention basins. From here it is pumped via windmill and solar pump to storage dams at the top of the hill and released as required for irrigation and to maintain the system. Movement of the water and the presence of frogs keep mosquito breeding grounds to a minimum.
Grey water from sinks, showers and laundries is collected and treated in separate wetlands. Its three stage treatment through gravel and reed bed wetlands traps nutrients and treats pathogens, resulting in water that is actually of drinking quality. However, as regulations do not allow treated grey water for potable uses, sub-surface irrigation pipes to a landscaped mound for evapotranspiration distribute it.
Roof water is collected and stored in the 43 building-integrated rainwater tanks. This water supplies the laundries in the student residences and the spray-mist cooling system for the student pavilion and lecture theatre. Even after water has been used for spray mist cooling, it is not wasted, but collected and cleansed in a small wetland for reuse in the system.
This careful use of water is further enhanced by reducing demand for its uptake, this most effectively through the use of dry composting toilets.
Landscaping (back to top of page)
As the site was degraded, it required extensive revegetation with plants selected for low water uptake. The planting program, other regenerative measures such as creek restoration, as well as a range of environmental monitoring activities are all closely linked into the School of Environmental Science's teaching program. This educational agenda has resulted in two approaches to landscaping: the first has been to plant most of the site with vegetation representing the major climatic regions of the Murray Valley; the second is the creation of an arboretum within the building precincts, planted within species which grow in ecologically similar vegetation regions of the world. Revegetation and the creation of extensive wetlands is providing significant habitat for local fauna fauna, with increases in bird and frog populations having been observed.
Wide shot of buildings showing landscaping of wetland areas
Waste management (back to top of page)
Throughout the campus there is a two bin system for separate collection of non-recyclables / food scraps and mixed clean recyclables. This has been determined by the waste services available from Albury City Council, which landfills non recyclables and separates recyclables at a Materials Recovery Facility (MRF). A contractor collects used office paper, though this is taken to the same MRF. These limited recycling services are due to lack of economies of scale in regional cities and towns (e.g. insufficient quantities of clean office paper are generated to be worth to be worth collecting separately and on-selling).
In the residences, food scraps are composted for use on a permaculture garden the students have established. The composting toilets, besides saving water, contribute to waste minimisation as they convert human waste into a byproduct that can be used as fertiliser (they have also saved the university the cost of either installing its own sewerage system or linking to the Council's and having to pay sewerage mains rates).
Social and cultural (back to top of page)
In many large projects, social and cultural benefits are largely add-ons; aesthetic improvements to the built environment, better street lighting, increased safety, maybe the provision of a park and so on. Thurgoona's social and cultural ambitions are far higher, in that it aims to provide an exemplary environment for low impact living. Through its carefully integrated systems of energy, water and waste management, it sets out to actually change behaviour and thus contribute to cultural change towards more sustainable ways of living and working. It will be some years before its success in this regard can be assessed. But the informal user survey carried out for this case bodes well.