Zero-energy buildings

This Issue This is a part of the Energy feature

By - , Build 107

Projects are underway in several countries on new towns and communities with zero-energy goals. In Singapore, Beca has been appointed to provide consulting engineering and project management services for a ground-breaking retrofit project.

Singapore’s zero-energy building due to open in 2009.

Singapore will soon have its first zero-energy building (ZEB) – one that produces as much energy from on-site renewable technologies as it consumes from the grid. New buildings provide the best opportunity for a zero-energy approach, as these can be purpose designed towards the lowest energy objective.

Changing existing building to a ZEB

One of the goals of the Singapore zero-energy building (ZEB) was to select an existing building for the project, to clearly demonstrate to the industry the potential for improvement in the environmental performance of the existing building stock and to stimulate change. The building will also serve as a showcase of green building technologies for education, training and research. It will house green classrooms and offices, as well as a visitor centre that will be used for training purposes.

Due for completion in mid 2009 and co-funded by the Ministry of National Development and the Economic Development Plan, Singapore’s ZEB is the flagship project for the Building and Construction Authority (BCA) Green Building Masterplan.

Live research lab

The BCA is working with the National University of Singapore to transform an existing block – a relatively standard 3-storey building with a floor area of approximately 3,000 m2 – at the BCA Academy in Braddell. The project aims to demonstrate the role of selected green building technologies and provide a live research lab for the university to research and evaluate the performance of these technologies in the Singapore climate.

Singapore’s zero-energy building due to open in 2009.

As well as testing approaches to improve the internal environmental quality in existing school classrooms, the project seeks to validate computational simulation approaches to more accurately predict energy and environmental performance for future building designs. These findings will be shared with the scientific community.

The existing building is orientated on a north-south axis with main façades facing east and west. This is at odds with the preferred east-west axis for tropical design, as east and west facing windows are difficult to control in Singapore with the lower sun heights.

Solar or photovoltaic cells covering 1,295 m2 are planned for the roof and façade of the building. These will convert light into electricity and will be used to power artificial lights, office equipment and air-conditioning. Although also connected to and drawing power from the main grid, the building will feed back into that grid the same amount from clean energy sources. The photovoltaic installation is estimated to provide approximately 186,000 kWh of electricity per year.

ZEB green features

The ZEB boasts a range of other green features, including:

  • high-performance building envelope, with climate responsive façade design
  • single coil twin-fan ventilation system to regulate the flow of fresh and recycled air according to demand
  • sensors to detect the presence of users, and fresh air, which requires more energy to chill than recycled air, only channelled to occupied rooms
  • a personalised ventilation system
  • solar chimneys, a technology developed for the tropical climate – constructed of metal that absorbs solar radiation, they induce warm air from a high level in the classrooms and non-air-conditioned spaces, with air passively replaced by cooler fresh air
  • vertical greening, where shrubs are planted on a wall’s façade to reduce heat gain
  • daylight enhancement devices to redirect natural light to reduce energy use
  • automatic lighting controls to reduce artificial lighting requirements when daylight is available and turn off lights in unused areas
  • a building management system (BMS) that automatically controls the various systems to balance comfort and energy efficiency. Data will be used for education and research purposes.

Costs and payback

The construction cost premium of the ZEB is estimated to be approximately 10% more than a typical office building, with an estimated payback of about 11–12 years. It is also expected to be 60% more efficient than a conventional commercial office building, with the savings from energy efficiency gains expected to be S$48,000 per year.

ZEBs in New Zealand

Beca sees the project’s ambitious goals as admirable. They could also be applied in New Zealand to improve the performance of existing buildings and reduce energy use. Several New Zealand projects have used photovoltaics, with Auckland International Airport Ltd recently commissioning the largest building-integrated photovoltaic installation in New Zealand at 220 m2. Building-integrated wind turbines are also being trialled on a number of Wellington buildings.

New Zealand has similar issues to those faced by the industry in Singapore, with a need to improve the environmental performance of the existing building stock, but New Zealand has a better climate than Singapore for the application of climate-responsive design and a significantly better solar resource.

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Singapore’s zero-energy building due to open in 2009.