A High Performance Building North of the Border in Canada
The Norman-Maurice Building in Montreal, which comprises offices for the Canadian Royal Mounted Police and the Naval Reserve, was designed and built to be a prototype for green and sustainable building standards in Canada. This very project is profiled in the current issue of High Performance Buildings. (Spring, 2009)
In Canada, as we know, the winter season is long and features extreme low temperatures. This factor alone, poses a challenge to maintaining energy savings while also providing for adequate ventilation, especially when employing natural ventilation to the building year-round. The engineers and design team got around this by using a hybrid mechanical and natural ventilation system, that features motorized windows at the top level of skylights that open when temperature and weather conditions permit, to provide for as much natural ventilation as possible in this climate range. Also, as per LEED credit requirements, windows that can be manually opened were placed accordingly in occupied spaces.
As the article later points out, the skylights also provide another LEED credit area in Indoor Environmental Quality, that being daylight to occupied spaces.
The mechanical ventilation is accompanied by a dedicated outdoor air source high efficiency heat recovery system (Enthalpy Wheels or Heat Pipes) that takes heat from the exhaust air to heat the incoming air, and is humidified when needed by an adiabatic humidification process when warranted during the dry winter months. The indoor air is monitored for CO2 levels, and as such, incoming fresh air brought in on as needed basis, to maximize energy savings, while maintaining IAQ.
Another feature that this building features is becoming more common today, and that is an Underfloor Air System. With this system, ventilation (and/or heating) is supplied via a network of underfloor plenum's with the use of pressurized air. The air is distributed via floor registers to the occupied spaces by the use of low-velocity supply. This technique provides for adequate IAQ at the occupied levels, but less so at higher levels. To address this, the current ASHRAE Standard 62.1 -2007 suggests an efficiency of 120 percent which will then allow for a 17 percent reduction in the needed outside air -- VERY important in a cold climate. Luckily, there is another benefit to this: the return air is warmer, reducing cooling loads as more sensible and less latent cooling is needed. The major design advantage here is that the occupied space areas are not compromised with duct work that otherwise could interfere with placement equipment, furniture and general room / office floor layout.
Heating and cooling for the building is done by for the most part with fluid-based radiant ceiling slabs. The major advantage here is energy savings due to the fact that power needs are reduced versus using a traditional air-based system. As this employs more active area to the heat / cool transfer system, fluid temperatures very close to that of the room are possible, meaning less temperature differential is needed. In the winter, it allows for a lower temperature heating supply fluid, which saves energy, while in the summer, it minimizes condensation, which can be a major source of mold. Mold, as we know, is an increasing issue with health and indoor air quality. Where needed, the air is dehumidified during wet periods to further deal with this risk.
These slabs play yet another role -- once again, the concept of synergies and trade-offs seen in Integrated Building Design -- that is they are a Thermal Mass. This allows for heat to be stored during off-peak hours, dramatically reducing peak hour heating and cooling loads. These Thermal Mass systems are capable of delaying the loads for 12 hours, meaning that heating can be done during warmer periods of the day, while cooling can be done during the cooler hours of the night. Due to the large thermal inertias, it was necessary to employ zoning and also to use the underfloor air system to provide additional cooling when needed. Careful attention was paid to the external facing slabs, so that the temperatures could vary as needed, while the internal slabs were maintained at a constant temperature year-round.
A Central Energy Plant was used which features three HFC-based chillers -- one water cooled and the other two air cooled, along with two gas-fired boilers. The boiler use is minimized. In addition, a geothermal heat exchanger was included. It is interesting to note that the indoor portions of this building need chilled water year-round, allowing for the heat that this absorbs to be reclaimed by the heat exchangers build into the design.
During the winter season, the solid thermal energy storage system preheats returning water by day and then this system is recharged at night by the water-cooled chiller at night, which acts as a consumer. Naturally, the reverse happens during the summer months. The aim here is to avoid having to use the gas-fired boiler, and the back-up chiller as little as possible.
Regarding the geothermal heat exchanger, it is is a Vertical Exchanger that consists of of 60 450 foot deep bores. This was able to achieved by employing the above mentioned Thermal Storage to reduce the original calculated need for 100 bore holes, which were not feasible at this site, due to space limitations. In addition to the radiant slab ceilings, it was found that there was contaminated soil that had to removed from the underneath of one of the buildings. This, in turn, provided the opportunity for a solid thermal energy storage system to be used as well. As the area was excavated, the perimeter was insulated, and multi-layers of PEX piping were laid in the back-fill sand. This was unique to this application, as most thermal storage systems were found to be fluid-based.
Two observations were noted here -- first, that heat was not uniformity distributed along the piping, but rather followed a pattern that required the utilization of reverse flows. Secondly, it was found that heat penetrated only to radius of 4 inches from the pipe, necessating a 9 inch spacing between the PEX pipes so that thermal interference between charging and discharging cycles were limited.
All control systems are direct digital which minimize the need for manual operation.
The cost effectiveness of this building exceeded all expectations. The designers sought to reduce energy use by 50 percent as compared to the 1997 Model National Energy Code for Canada. The total cost of this building was $45 million CND, which included 1.5 million on sustainable development and $10 million on the mechanical and electrical systems. The use of the Solid Thermal Storage System reduced the size of the geothermal heat exchanger by 40 percent, which not only saved cost, but reduced the construction carbon foot print of the building -- an important, but often over-looked item.
In order to obtain LEED certification in Canada, an energy simulation program called EE4CBIP was designed to show that the building complied with Canada's Commercial Building Incentive Program. This served to establish the building's energy performance. the program estimated that the heating would have a coefficient of power (COP) of 2.5 during heating (due to the lower ground temperatures in Canada) and a cooling COP of 4.5.
The reference MNECB-compliant was 11.17 MBtu/ SF, while the building itself was estimated to use only 6.34 MBtu/ SF, a 48.5 percent reduction in energy use. It was found that during the 2006 2007 period, that the building used only 9.327 MBtu of electricity and 1,509 MBtu of natural gas for a total of 10,862 MBtu or only 4.75 MBtu/ SF. When compared to the reference building described in the above mentioned calculations, this actual usage indicates that the building is using 61 percent less energy than a standard building, with a cost savings of 55 percent. Thus, the projected cost savings of $172,000 CND turned out to be $246,000 CND. This means that over a 25 year period, over $6 billion CND will be saved, and the pay-back period will be six years.
It was also emphasized that an annual reduction of 800 tons of CO2 was seen. In addition, as mentioned above, sustainable building practices were used. These included incorporating the original foundry building facade into the new building, the reclamation of 100 percent of the steel materials, 82 percent of the wood and 92 of the brick.Over 75 percent of the materials from the old buildings were diverted from landfills, and over 80 percent of the new building materials were recycled. Low emitting materials were used whenever possible, and the concrete used contained 27 percent fly-ash to replace cement.
Water savings were also achieved to an overall rate of 30 percent for potable use and 50 percent for sewer flows. Gray-water collection, dual-flush toilets and low flow urinals play a part here.
Daylighting and passive solar heating were emphasized, by orienting these to the south, and providing shading that allowed for summer shade, but winter sun to penetrate and warm the large areas of masonry walls and concrete in the building. A green roof is also featured, and is accessible by the occupants.
In Canada, as we know, the winter season is long and features extreme low temperatures. This factor alone, poses a challenge to maintaining energy savings while also providing for adequate ventilation, especially when employing natural ventilation to the building year-round. The engineers and design team got around this by using a hybrid mechanical and natural ventilation system, that features motorized windows at the top level of skylights that open when temperature and weather conditions permit, to provide for as much natural ventilation as possible in this climate range. Also, as per LEED credit requirements, windows that can be manually opened were placed accordingly in occupied spaces.
As the article later points out, the skylights also provide another LEED credit area in Indoor Environmental Quality, that being daylight to occupied spaces.
The mechanical ventilation is accompanied by a dedicated outdoor air source high efficiency heat recovery system (Enthalpy Wheels or Heat Pipes) that takes heat from the exhaust air to heat the incoming air, and is humidified when needed by an adiabatic humidification process when warranted during the dry winter months. The indoor air is monitored for CO2 levels, and as such, incoming fresh air brought in on as needed basis, to maximize energy savings, while maintaining IAQ.
Another feature that this building features is becoming more common today, and that is an Underfloor Air System. With this system, ventilation (and/or heating) is supplied via a network of underfloor plenum's with the use of pressurized air. The air is distributed via floor registers to the occupied spaces by the use of low-velocity supply. This technique provides for adequate IAQ at the occupied levels, but less so at higher levels. To address this, the current ASHRAE Standard 62.1 -2007 suggests an efficiency of 120 percent which will then allow for a 17 percent reduction in the needed outside air -- VERY important in a cold climate. Luckily, there is another benefit to this: the return air is warmer, reducing cooling loads as more sensible and less latent cooling is needed. The major design advantage here is that the occupied space areas are not compromised with duct work that otherwise could interfere with placement equipment, furniture and general room / office floor layout.
Heating and cooling for the building is done by for the most part with fluid-based radiant ceiling slabs. The major advantage here is energy savings due to the fact that power needs are reduced versus using a traditional air-based system. As this employs more active area to the heat / cool transfer system, fluid temperatures very close to that of the room are possible, meaning less temperature differential is needed. In the winter, it allows for a lower temperature heating supply fluid, which saves energy, while in the summer, it minimizes condensation, which can be a major source of mold. Mold, as we know, is an increasing issue with health and indoor air quality. Where needed, the air is dehumidified during wet periods to further deal with this risk.
These slabs play yet another role -- once again, the concept of synergies and trade-offs seen in Integrated Building Design -- that is they are a Thermal Mass. This allows for heat to be stored during off-peak hours, dramatically reducing peak hour heating and cooling loads. These Thermal Mass systems are capable of delaying the loads for 12 hours, meaning that heating can be done during warmer periods of the day, while cooling can be done during the cooler hours of the night. Due to the large thermal inertias, it was necessary to employ zoning and also to use the underfloor air system to provide additional cooling when needed. Careful attention was paid to the external facing slabs, so that the temperatures could vary as needed, while the internal slabs were maintained at a constant temperature year-round.
A Central Energy Plant was used which features three HFC-based chillers -- one water cooled and the other two air cooled, along with two gas-fired boilers. The boiler use is minimized. In addition, a geothermal heat exchanger was included. It is interesting to note that the indoor portions of this building need chilled water year-round, allowing for the heat that this absorbs to be reclaimed by the heat exchangers build into the design.
During the winter season, the solid thermal energy storage system preheats returning water by day and then this system is recharged at night by the water-cooled chiller at night, which acts as a consumer. Naturally, the reverse happens during the summer months. The aim here is to avoid having to use the gas-fired boiler, and the back-up chiller as little as possible.
Regarding the geothermal heat exchanger, it is is a Vertical Exchanger that consists of of 60 450 foot deep bores. This was able to achieved by employing the above mentioned Thermal Storage to reduce the original calculated need for 100 bore holes, which were not feasible at this site, due to space limitations. In addition to the radiant slab ceilings, it was found that there was contaminated soil that had to removed from the underneath of one of the buildings. This, in turn, provided the opportunity for a solid thermal energy storage system to be used as well. As the area was excavated, the perimeter was insulated, and multi-layers of PEX piping were laid in the back-fill sand. This was unique to this application, as most thermal storage systems were found to be fluid-based.
Two observations were noted here -- first, that heat was not uniformity distributed along the piping, but rather followed a pattern that required the utilization of reverse flows. Secondly, it was found that heat penetrated only to radius of 4 inches from the pipe, necessating a 9 inch spacing between the PEX pipes so that thermal interference between charging and discharging cycles were limited.
All control systems are direct digital which minimize the need for manual operation.
The cost effectiveness of this building exceeded all expectations. The designers sought to reduce energy use by 50 percent as compared to the 1997 Model National Energy Code for Canada. The total cost of this building was $45 million CND, which included 1.5 million on sustainable development and $10 million on the mechanical and electrical systems. The use of the Solid Thermal Storage System reduced the size of the geothermal heat exchanger by 40 percent, which not only saved cost, but reduced the construction carbon foot print of the building -- an important, but often over-looked item.
In order to obtain LEED certification in Canada, an energy simulation program called EE4CBIP was designed to show that the building complied with Canada's Commercial Building Incentive Program. This served to establish the building's energy performance. the program estimated that the heating would have a coefficient of power (COP) of 2.5 during heating (due to the lower ground temperatures in Canada) and a cooling COP of 4.5.
The reference MNECB-compliant was 11.17 MBtu/ SF, while the building itself was estimated to use only 6.34 MBtu/ SF, a 48.5 percent reduction in energy use. It was found that during the 2006 2007 period, that the building used only 9.327 MBtu of electricity and 1,509 MBtu of natural gas for a total of 10,862 MBtu or only 4.75 MBtu/ SF. When compared to the reference building described in the above mentioned calculations, this actual usage indicates that the building is using 61 percent less energy than a standard building, with a cost savings of 55 percent. Thus, the projected cost savings of $172,000 CND turned out to be $246,000 CND. This means that over a 25 year period, over $6 billion CND will be saved, and the pay-back period will be six years.
It was also emphasized that an annual reduction of 800 tons of CO2 was seen. In addition, as mentioned above, sustainable building practices were used. These included incorporating the original foundry building facade into the new building, the reclamation of 100 percent of the steel materials, 82 percent of the wood and 92 of the brick.Over 75 percent of the materials from the old buildings were diverted from landfills, and over 80 percent of the new building materials were recycled. Low emitting materials were used whenever possible, and the concrete used contained 27 percent fly-ash to replace cement.
Water savings were also achieved to an overall rate of 30 percent for potable use and 50 percent for sewer flows. Gray-water collection, dual-flush toilets and low flow urinals play a part here.
Daylighting and passive solar heating were emphasized, by orienting these to the south, and providing shading that allowed for summer shade, but winter sun to penetrate and warm the large areas of masonry walls and concrete in the building. A green roof is also featured, and is accessible by the occupants.
Posted by Alan L. Englander at 4/11/2009 3:18 PM 
Categories: Cost-Effectiveness, Natural Ventilation, Geothermal, Sustainable Building, Thermal Mass, Solid Energy Storage, High Performance Buildings, Underfloor Air System
Categories: Cost-Effectiveness, Natural Ventilation, Geothermal, Sustainable Building, Thermal Mass, Solid Energy Storage, High Performance Buildings, Underfloor Air System
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