| The University of Southampton, one of the UK’s top ten universities based on research, has 20,000 students and 5,000 staff members based across several campuses in Winchester and Southampton. A new engineering, education and reception building will be constructed during 2005/2006 as part of the university’s continuing development of its Highfield campus in Southampton. Designed as a keynote building and given a prominent location along University Road (Figure 1), the 90-m (300-foot) -long, 18-m (60-foot) -wide four-storey building will provide 5700 m2 (62,000 square feet) of useable area to create a:
• Reception point for the university
• Security control centre
• 360-seat lecture theatre
• Engineering research centre
• Education and teaching areas
• Internet café area.
The architectural concept for the building was to create a glazed street facade along the entire length of the west side, forming a “window” into the building and acting as a link between the floors.
PB was commissioned to provide mechanical and electrical (M&E) design services. The aim of the entire design team was toward achieving a more sustainable development, with our emphasis being on low-energy design solutions.
Designing for the Future
As with any major new building, achieving a sustainable design solution presents challenges that must be taken seriously if we are to slow down or even help to reverse some of the environmental impacts that construction inevitably brings. With this point in mind, we investigated a number of different servicing solutions to determine the most appropriate applications for this building. Those that were implemented are discussed below.
Natural Ventilation. The use of natural ventilation was maximised and, hence, the need for mechanical refrigeration to provide cooling in the summer was reduced. To maximise natural ventilation, we conducted thermal modelling of spaces to determine if satisfactory internal comfort conditions could be maintained without mechanical refrigeration. Whether or not this was possible depended on the size, type, and shape of the window; the amount of airflow that was delivered when the window was open; and the internal heat gains of the space. We usually managed to prove that natural ventilation was possible in all single occupancy offices in the building with an acceptable range of temperatures in the space over the summer months.
Figure 1: Site Plan for Proposed Engineering Educational and Reception Building.
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Figure 2: Photovoltaic cells as part of the building fabric. |
Figure 3: Results from CFD model of "the street" (shades of grey correspond to temperature variations through the vertical section). |
Figure 4 : Computer generated rendering of the building at the scheme design syage. |
Pre-cooling. The thermal mass of the building was used as a heat sink, which in conjunction with night-time ventilation, provided a means to pre-cool the building prior to occupation over the summer. To achieve “night time cooling,” the building structure must be exposed. In our case this was achieved through the absence of false ceilings in the building. All services at high level are on display and the soffits of the concrete slabs form the finished surface for the rooms. During the summer, cooling is achieved by opening the windows at night.
Absorption Chiller. Cooling for those spaces that require mechanical refrigeration was provided via an absorption chiller, which makes use of “waste” heat available from the central combined heat and power (CHP) plant on the campus to generate low temperature hot water. In turn, this water is used to heat buildings or generate hot water for buildings. This arrangement achieves an overall system efficiency that represents a vast improvement over a conventional power station and has less of an impact on the environment. As an added benefit, the absorption chiller uses water as refrigerant, so the environmental impacts associated with hydroflourocarbon-based alternatives are avoided.
Heat Recovery. Heat recovery and free cooling strategies were used in the design of the ventilation and heat rejection plant to minimise the overall energy use of the building. Heat recovery was achieved by installing thermal wheels in the building’s air handling plant. These wheels recover heat from the exhaust air to pre-heat the cold fresh air supply air in winter. Free cooling is achieved by smart control of the air handling plant. If the outside air temperature is such that it does not require cooling prior to supply into the building, then the refrigeration plant is kept off. Free cooling also includes the night time cooling discussed above.
Rainwater Attenuation. Attenuation of rainwater on the site is provided to reduce the flow of water to the drainage infrastructure during a heavy storm and help to alleviate overloading on the existing system.
Solar Power. Photovoltaic cells (Figure 2) will be installed on the roof to generate electricity from solar energy. These will also be used for research purposes as part of the university’s ongoing study of renewable energy.
Solar Heating and Cooling. We had to incorporate the full-height glass w all stretching 90 m (300 feet) along the street and comply with Part L of the Building Regulations, which set strict guidelines for the quantity of glass in a building in order to reduce the energy consumed for heating and cooling. The design strategy for the glazed wall was to provide no heating or cooling during winter and summer respectively. The design aims to make use of the solar energy through the glass to generate more “temperate” conditions in winter on the ground floor areas around the reception desks, the internet café and lecture theatre circulation space, which represent 15 percent of the floor area of the building. This design approach represents an energy-efficient means of connecting the various spaces in the building whilst fulfilling the client’s desire for a “window” into the building.
Systems we studied but discounted for various economical and performance reasons included:
- Borehole water for cooling
- Closed circuit ground loop for heat rejection of the cooling system
- Rainwater harvesting
- Grey water recycling
- Sustainable drainage systems
- Termodeck, which is a trade name for a system by which ventilation air is introduced into the occupied space via ducts formed in the structural slabs in the building, thus making use of the thermal mass of the structure as a heat sink.
Computational Fluid Dynamics is a Valued Tool
To achieve sustainable solutions, we rely increasingly on sophisticated modelling tools that assist in predicting how a space or a zone will perform under certain design conditions. One such tool is computational fluid dynamics (CFD), which we used to predict temperatures and air flows in the street area of the building, and to assist in designing the space to achieve optimal internal conditions in summer and winter, designing the external shading devices (Figure 3), selecting the type of glass in the glazed elements, and determining the area of openings required to achieve the natural ventilation in “the street.”
Computational modelling allowed all proposed designs to be tested quickly and enabled the designers to proceed with confidence, knowing that the most economically viable solutions were being achieved with maximum environmental consideration. Modelling the designs also allowed rapid prototyping to verify the designs. Testing these designs would not have been feasible in a real life situation.
Conclusion
Figure 4 shows a computer generated rendering of the building, demonstrating a scheme that achieves “landmark” status. The building design, layouts and servicing options reflect the consideration given by the entire design team, owner and user groups to the ever more stringent environmental regulations aimed at preserving energy throughout a building’s life cycle. |
