One of the fastest growing communities in British Columbia, the City of Richmond, has recently built a new city hall. The city council envisioned its new facility to be a landmark building and also wa...
One of the fastest growing communities in British Columbia, the City of Richmond, has recently built a new city hall. The city council envisioned its new facility to be a landmark building and also wanted it to be environmentally sensitive. The designers were asked to use “state of the art” sustainable design principles.
The new structure located in the heart of the city was completed last summer. It has an eight-storey administration tower and a two-storey multi-purpose wing and council chamber. About 310 people are expected to occupy the 11,150 m2 space.
Previously the city’s public services were provided in several buildings throughout Richmond, and some of these had serious HVAC problems and associated indoor air quality concerns. Consequently, the city had a number of requirements for the new building’s HVAC design.
The first concern was air quality. Stantec and the design team specified a four-pipe fan coil system for heating, cooling and ventilation. The system is designed to supply to the occupied areas almost double the amount of outside air that is prescribed by ASHRAE 62-99. The system improves the indoor air quality and allows the HVAC system to operate in a compartmental configuration, thus promoting better thermal zoning so that heating and cooling respond to space demand. Only the areas of the building requiring 24-hour air conditioning, such as the computer rooms, are served from independent HVAC systems.
The building ventilation air is provided by two central make-up air handling units located in the penthouse mechanical room. The unit serving the low-rise areas has variable air volume control (VAV) to provide demand ventilation to the multi-purpose meeting rooms. The use of duct liner was minimized to reduce the potential contamination of the ventilation air.
The second concern was that the building would operate at a lower than normal energy level. The building was modeled using the U.S. Department of Energy (DOE) hourly computer program to optimize the building siting, envelope, lighting and HVAC systems. The general results of the simulations indicated the city hall would consume 26.4% less energy compared to a building designed to meet the requirements of Canada’s Model Energy Code for Buildings (MNECB). This result was achieved even with the higher than normal ventilation rates. The total energy consumption of the installed design is 79,600 Gigajoules, and the estimated yearly savings are $32,700. The building also qualified for a rebate of $65,350 from NRCan’s Commercial Buildings Incentive Program.
The building envelope was carefully designed using frittered glass on the west exposure to reduce solar gains into the occupied areas. Also, a two-storey atrium helps to minimize the heat losses by acting as a buffer zone controlling solar gains to the multi-purpose areas. Most of the energy savings — 55% — are due to the operating efficiency of the designed four-pipe fan coil system. The next biggest saving is from the lighting system.
A third concern was to minimize carbon dioxide (CO2) pollution. In addition to the CO2 emissions saved as a by-product of the energy efficient design, the use of high efficiency condensing boilers to provide heating water save in excess of 55 metric tons of CO2 per year compared to a mid-efficiency boiler plant. The high efficiency boilers cost approximately $20,000 each more than mid-efficiency boilers (minus a $9,000 rebate from BC Gas), but the payback is less than five years. Because of the design of the building the size of the chiller is considerably reduced.
The client wanted the occupants to be able to open their windows without penalizing the building’s energy consumption. The solution was to provide opening windows with sensors that interlock with the mechanical system and prevent the system being driven to operate at 100% on a very cold day. The sensor maintains the local fan coil unit in the control command position it had for heating the space before the window was opened. Cooling is locked out.
The mechanical systems are controlled by an automated building energy management control system (EMCS) which uses an integrated structured cable system and is connected to the city-wide area network.
The mechanical system has to be rugged and easy to maintain. Therefore, special attention was given to the placing of components to be serviced, such as the fan coil units outside the occupied areas. Finally, the energy design is designed to be flexible and capable of being upgraded in the future. Super insulating windows, for example, could save an additional 5.45% energy. Or, the four-pipe fan coil system could be easily modified to accommodate a geothermal upgrade, such as switching to natural ventilation in lieu of the mechanical ventilation system, and installing a ground source heat pump geothermal heating and cooling system. If the cost of fuel continues to increase, this option will become viable in the near future.
|Window U-value: 2 W/m2C|
|Percentage of fenestration: 66% (MNECB only permits 40%)|
|Boiler plant efficiency seasonal: 88%|
|Outdoor air ventilation quantity: 1.1 l/s/m2|
|Equipment power density: 7.4 W/m2|
|Total budget: $30 million|
|Total cost of mechanical: $2.5 million|
|HVAC system only: $1.6 million (approx. $12/sq. ft.).|
Owner: City of Richmond
Mechanical: Stantec Consultants, Vancouver (Joe Tai, P.Eng., Alf Hartviksen, P.Eng., Paul Marmion, P.Eng., Jimmy Ng., P.Eng.)
Electrical: R.A. Duff & Assoc.
Structural: Bush Bohlman & Partners
Building Environmental Consultants: Stantec, G.F. Shymko & Assoc., Dr Ray Cole
Project manager: Dominion Company
Architects: Hotson Bakker and Kuwabara Payne McKenna Blumberg
Photos: courtesy the architects