The John Henry Brookes Building has a passive design philosophy. Natural daylight is maximised wherever possible in the building, but solar gain (overheating due to excessive sunlight) is kept to a minimum, as is heat loss in the winter. By incorporating features that manage how light enters the building into the design, the natural ventilation of the building is more effective and is a significant feature of the building’s comfort strategy.
In terms of buildings, ‘passive’ refers to how the flow of air in the building contributes towards the temperature and air quality management. The John Henry Brookes Building incorporates a substantial amount of exposed thermal mass (concrete) which acts as a heat sink. In the winter the concrete stores the warmth (in a similar manner to a storage heater) and in the summer it is cooled by opening windows during low occupancy night time hours. By cooling the concrete at night, the cooler temperature is stored in its mass, thus reducing the need for mechanical temperature management in the daytime.
Under the Piazza is a series of pipes that draws warm or cool fresh air into the building. You can find out more about how this works by reading the article Passive by design.
There are solar panels on both the Abercrombie extension and the John Henry Brookes Building. These panels contribute towards the supply of electricity to both buildings and also reduce, by approximately 4%, the buildings' carbon emissions.
Solar panels are made of a series of photovoltaic cells made up of layers of a semi-conducting material, typically silicon. As the panels absorb the light an electric field is created. While solar panels work at their optimum in strong sunlight, they do work at lower light levels too.
Using a combined heat and power plant will reduce the energy consumption of the John Henry Brookes and Abercrombie buildings by around 16%. The plant has been sized to provide the building’s heat requirements and work with the electrical demands of the building. Using this kind of system is also considered extremely efficient as producing the heat and electricity on-site generates less CO2 emissions than using electricity from the national grid.
As well as producing heat, the plant also helps cool the building in a process called 'trigeneration', in which an absorption chiller uses a refrigerant to cool the air.
The flow of water from the roofs of the John Henry Brookes Building is reduced as the green roof controls the flow and absorbs it. Controlling the flow of water from the roofs decreases the stress on the local sewer system during periods of high rainfall.
Additionally, a green roof can help towards managing the temperature of the building. In the summer, the vegetation will absorb light and prevent its energy from turning into heat energy and at cooler times of the year the substrate and plant layer will also act as an insulator, reducing the amount of heat being lost from the building.
With a selection of plant life, green roofs can also become a valuable habitat for insects and some avian wildlife.
To manage the run-off of rainwater from the roof of the John Henry Brookes Building there is a storage tank under the Central Courtyard. Around 50% of the run-off rainwater is collected, helping reduce this flow into the local sewer system. This grey water is then distributed to facilities in the building and re-used to flush toilets. This collection and re-use of rainwater helps to reduce the impact of the building on the local water and sewer systems.
The most recent addition to Oxford Brookes University’s student accommodation, Westminster Halls, integrates a number of features that enhance its sustainability credentials. All the roofs are sedum planted green roofs to reduce the flow of water run-off and provide a habitat for insect and avian wildlife.
Similar to the John Henry Brookes Building, an energy centre provides both the heat and a proportion of the electricity to the new Halls of residence. Inside the halls, each flat has a thermostat so the temperature can be managed according to users in individual flats. The innovative passive infrared (PIR) radiators also prevent heating rooms that are unused as the heating only turns on when the room is occupied.
Rated ‘Very Good’ by BREEAM (Building Research Establishment Environmental Assessment Methodology) the John Payne building provides attractive open-plan offices, plus a technology lab and workshop for the Faculty of Technology, Design and Environment. Sustainable features include a green roof, natural ventilation incorporated into the building management system and local meters to monitor and benchmark energy use.