A Grander View
When Enermodal Engineering decided to build a new headquarters on Lancaster Street West in Kitchener, southwest Ontario, we knew we had to set our sights high in terms of energy efficiency. As a leading green building consulting firm, we wanted a building that would showcase to our clients what is possible in today’s market — at a competitive cost — and to create Canada’s most energy efficient office. Now that we’ve lived in “A Grander View,” our new 2,040m2 office, for almost one full year, we know we have met our goal of using 65 kWh/m2. That figure compares with the Canadian average of 375 kWh/m2.
A variety of factors help set this triple LEED Platinum candidate (New Construction, Commercial Interiors, and Existing Buildings: Operations & Maintenance) office apart from a conventional office:
• a return to engineering basics
• a highly efficient, yet simple mechanical system
• recaptured waste water
• a site that was previously an urban infill gravel lot.
Engineering 101 — first reduce energy demand
Enermodal’s approach to energy efficient mechanical design has long been to reduce the building’s energy demands and then deliver the remaining energy needs in the most efficient manner possible. The first aspect of this mantra — reducing demand — is fulfilled through applying Engineering 101 principles such as proper building orientation, insulation, and windows.
Most offices suffer from unwanted glare and solar heat gain during the summer. The first way Enermodal addressed this problem was to orient the long building east-west, minimizing the east and west exposures.
An airtight building envelope is one of the most important elements in achieving a high-performance building. In fact, 34% of the energy consumed by buildings is lost through the building envelope. Insulated concrete forms (ICFs) are easy to install and give insulation value. To avoid thermal bridging (heat loss between two poor insulators), the construction team lined the window openings with insulation between the thick, concrete walls and the windows. Plywood bucks were used to protect the insulation. The ICF joints were sealed with tape to prevent moisture from penetrating the building shell.
Windows are typically the leakiest part of an office building, and this fact was especially pertinent at A Grander View which has a 3-m2 window near to every occupant. Therefore, the windows are triple glazed, low-e argon filled, with fibre-glass frames. Although these windows are expensive, the cost is offset because their high insulation value allowed us to eliminate perimeter heating. The main purpose of perimeter heating in most office buildings is to counteract drafty, poorly designed windows.
The windows at A Grander View are recessed deep into the walls to provide shading for the staff when the sun is high in the sky. To cope with low sun angles, the south, west, and east exposures feature automated exterior shades. The shades have integrated sensors that respond to incident solar radiation and cause the shades to lower when heat or glare is an issue.
The large windows were not only beneficial from the perspective of the employees’ health and happiness, but also for daylighting. Thanks to the ample daylight, the lighting power density is just 8 W/m2 — 38% below the energy savings required by ASHRAE 90.1.
A simple approach to HVAC
While many “green” building designs feature extremely complex, “sexy” mechanical systems, the approach taken by Enermodal was to simplify the mechanical system as much as possible.
Before entering the building, outdoor air travels through concrete earth tubes buried in a hill behind the office. The tubes temper the air using the ambient temperature of the earth, which decreases the amount of energy needed to bring the air to the desired indoor temperature.
Typical office buildings are heated by boilers and cooled by rooftop air-conditioning units. These two systems work independently of one another, and often at the same time. Simultaneously heating and cooling a space is never efficient! A Grander View’s mechanical design is efficient because one system provides heating and cooling, and never both functions at the same time. The building is heated and cooled by three rooftop air-source heat pumps — one pump for each floor.
Called a multisplit variable refrigerant flow system, the heat pumps are connected to 60 small fan coil units that are located throughout the building and distribute the heating or cooling. The system allows the occupants to control the temperature and humidity for their own small work areas. The fan coils are connected by piping that carries refrigerant. The refrigerant is sent through the piping by variable flow compressors that can work at very low speeds. These compressors allow the system to run with a reduced amount of energy, representing an improvement over most heating/cooling systems, which operate at full-on or full-off.
The entire system is controlled by thermostats and occupancy sensors that send a wireless infrared signal to the automation system integrated into the fan coils. This sophisticated automation system has on/off, heat/ cool, and fan and compressor speeds. Rather than a building automation system in the mechanical room controlled by a dedicated individual that tells the lights, ventilation, and heating/cooling when to turn on and off for the day, this system automatically turns on and off depending on the actual occupancy of a given space.
Server rooms that house computer equipment typically generate a significant amount of heat. At A Grander View this heat is reused to provide the building’s domestic hot water pre-heating demand through an air-to-water heat pump. The approach also reduces the amount of energy needed to cool the server room.
These measures help Enermodal achieve 82% actual energy savings compared with Canada’s Model National Energy Code for Buildings (MNECB).
Energy efficiency and non-potable water
The non-potable water needs of the building, such as toilet flushing, are supplied by a 30 m3 rainwater cistern. A significant energy user in most cistern systems is a series of filters to remove sediment from the water before it is delivered. To eliminate those filters, the cistern system at A Grander View has the following elements:
• Rainwater initially passes through a screen to remove most sediment;
• Water is delivered to the cistern at a reduced rate so as to not disturb the sediment at the bottom of the cistern;
• The pump that takes the cistern water into the building floats near the top of the water level rather than being located near the bottom of the cistern.
The resulting water is cleaner, and the overall system more energy-efficient, than a conventional cistern.
Although most of the cistern water comes from roof-collected rainwater, Enermodal receives additional potable water from recapturing and using heat pump condensate created during the building cooling process. At peak cooling season (when rainwater would also be scarcest), the cooling process will produce 20 litres per hour (enough to flush a toilet five times).
Design around what’s salvageable
While the inner workings of the mechanical system are the most innovative aspect of the building, other aspects, such as the selection of exterior materials and landscaping choices also contribute to its sustainability.
The use of salvaged materials requires a fundamental change in the way architects design buildings. Rather than coming up with their ideal aesthetic and specifying a certain amount of each material, architects must find out what salvaged materials are available and then design around the quantities available. For example, A Grander View’s exterior features stone salvaged from a local demolished church. Once all the stone was used, other materials, such as recycled steel, FSC-certified cedar, a
nd stucco helped to soften the unrelieved faade of this long, rectangular building.
Another salvaged material, stone from the famed St. Clair River Tunnel in Sarnia, was used in a retaining wall and to enclose the employee garden plots.
Previously an urban infill gravel lot overlooking the picturesque Grand River, the site is now landscaped using only native, drought-tolerant species plants. They provide habitat and sustenance for wildlife and require no irrigation.
Stephen Carpenter, P. Eng. is president of Enermodal Engineering, which has offices in Kitchener, Calgary, Edmonton, Winnipeg, and Toronto.
Mechanical, electrical, structural, civil engineering, LEED/energy efficiency, commissioning and energy monitoring: Enermodal Engineering (Stephen Carpenter, P. Eng., Richard Lay, P. Eng., Tim Dietrich, P. Eng., Farid Ahmed, P. Eng., Victor Halder)
Architect: Robertson Simmons architects
Enermodal Engineering was one of the first Canadian consultants to specialize in green building design and has been honing its skills in this area for 30 years. To date the firm is the LEED consultant for 40% of LEED Canada-certified projects -five times more than any other consulting firm.
When the company recently built itself a new head office in Kitchener, Ontario, not surprisingly the consultants took advantage of their experience to combine in it the most effective green building strategies they know. The result is a building that they describe as “Canada’s most energy efficient office,” one that uses only 65 kWh per square metre.
CCE asked Stephen Carpenter, P. Eng., Enermodal’s founder and president, to explain some of its features and how they amount to such remarkable energy savings.