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THE HAGEN HAED OFFICE PROJECT

In 2006, the new head office for Hagen, a manufacturer and distributor of pet products, officially opened. This three-storey, 5,686-square foot corporate building located in Baie d’Urfé houses laboratories, storage space and a loading dock, service facilities (cafeteria, gym, etc.) as well as administrative offices. With a contemporary and stylized look, the building’s architecture is a reflection of the company’s desire to be a North American leader while continuing the commercial development already begun in Europe.

Originally created by following the usual parameters of a turnkey project, the concept slowly became a more ecological, and in tune with both the client’s and the different professionals’ corporate vision. Between this new vision and the formal integration of environmental strategies recognized by the LEED certification, there was only one step remaining!

With a predetermined site and an approved architectural concept as a starting point, the team undertook a global evaluation of the project, to unveil the sustainable development strategies that could be harmoniously integrated to the project. The chosen strategies reduce the impact of the development on the site, the consumption of drinking water and energy. They also favour a better use of the material resources and offer building users quality interior space.

At this point, we will discuss the project’s energy efficiency aspects in more detail. Over a building’s life cycle, the operating costs are actually higher than those generated during construction. The older the building gets, the more important this aspect becomes. In this particular instance, the Hagen head office’s estimated life expectancy is approximately 50 years.

To reduce the operational costs related to energy consumption, the goal was to create a building that was at least 50% more energy efficient than the standards dictated by the Model National Energy Code for Buildings.

As a starting point, the team’s mechanical engineers made a comparative study of the different systems available that were applicable to the project’s context. By weighing each option’s pros and cons, they concluded that a geothermal system with liquid-to-liquid heat pumps would be the most appropriate to reach the efficiency goals that were set.

The rectangular geometry of the building, as well as the presence of a central atrium, represented the elements of the initial course drawn when the mechanical systems were conceived. Indeed, the building’s orientation along an east-west axis reduces the considerable thermal charges that usually occur during the transition periods (spring/fall), when the solar rays’ angle is low. Along the southern glass front wall, the presence of trees constitutes a screen whose efficiency is not negligible (fig. 2 and 3). In the center of the structure, the atrium, which rises over three floors, is essentially the building’s lung. Fresh air is incorporated through it then distributed to all the offices and rooms through a system of transfer fans located between the ceilings.

The Hagen building’s HVAC system is made up of the following four main elements (fig. 2):

1. A heating power station in the basement, made up of 14 parallel heat pumps operating with a geothermal loop that simultaneously produces hot and cold water (fig. 4), 2 conduits (hot/cold water) with pumps that cover every zone in the building, a geothermal conduit (fig. 3 and 5) with pumps and two heat banks to store the heat;

2. Radiant slabs to heat areas along the outside wall;

3. An HVAC system, with air heaters and fan-coil units, spread throughout the building;

4. A fresh air handling unit, located on the roof of the building.

During the technical design of the systems, the team displayed some innovative thinking as they integrated heat banks. This system consists of two concrete bunkers packed with wet sand into which three rows of conduits have been inserted. The purpose is to store heat then by using a heat recovery wheel joined to the ventilation unit on the roof.

Thermal stations are generally used in large commercial cooling systems to make ice during the night. During the day, instead of (or in addition to) using coolers, the accumulated ice thaws which air conditions the building. Thus, the peak demand in electricity (the kW on the bill) and, as a direct result, the energy consumption are reduced since the change of ice tank is done with equipment that operates as much as possible at the energy efficiency’s optimal point. The use of the change of phase of water allows for the storage of more energy in less space.

When it comes to heating, this type of equipment is highly unusual since there no change of phase material needs to be used to store heat at the heating temperature. There is very little documentation on this application, while ice banks have been widely used and studied. In this particular case, there are two banks of wet sand and 13 rows of conduits running through it, installed in a fashion similar to radiant floors. During the night, hot water produced by the heat pumps runs through the banks to heat them (fig. 6), while during the day, the water returning from the building’s heating equipment runs through the hot banks. The peak demand in electricity is therefore reduced by the equivalent of two heat pumps. Wet sand allows more heat storage than dry sand. Based on the project engineer’s studies and computer simulations, it was determined that the optimal spacing for the conduits in wet sand should be nine inches, for a daily loading/unloading cycle.

 Before releasing the building’s evacuated air outside, the ventilation unit (DOAS) takes it through a heat recovery wheel. In the winter, heat and humidity are recovered from the evacuated air and transferred to the fresh air entering the building. Conversely, in the summer, the wheel transfers heat and humidity from fresh air entering the building to the evacuated air.

Though the use of quality equipment and the latest high technology systems is essential in the conception of a highly energy efficient building, teamwork remains vital to create a coherent, functional, economical and aesthetic whole.  

• The R value of the building’s envelope as well as its construction specifics;

• The dimensions of the windows, which harmonize the needs in terms of natural lighting and the control of thermal charges;

• Maximizing the supply in natural light, by using different types of glass and reflecting shelves to reduce the need for artificial light and, as a direct result, the charges for lighting and ventilation;

• Open-grid ceilings along the perimeter allows the slabs to radiate both up and down;

• Light work features, such as the use of a rug whose low R value does not interfere with the performance of the radiant floor.

The definitive results of the building’s energy performance serve to prove the theoretical values from the simulations and calculations made during its conception. The building’s energy performance is approximately 60% superior to that of a building of the same category, designed according to the Model National Energy Code for Buildings. In terms of numbers alone, this works out to approximate annual savings of 1,000,000 KWh, or $90,000, based on 2007 prices, equivalent to 300 tons of greenhouse gas. According to the analysis made by the project’s mechanical engineer, the savings in energy costs and the subsidies received will allow a return on the investment after approximately estimated at 7 years.

The impact of the “green“ approach to the building of the Hagen head office will undoubtedly have positive repercussions on the company’s clientele as well as its suppliers, visitors, competitors, contractors and subcontractors who contributed to the project. This corporate vision of sustainable development will certainly have a domino effect on similar companies who, in turn, will see a potential benefit in such an approach.

Project team:

Client: Rolf C. Hagen Inc.

Client Rep.: Les Entreprises Dahltan Inc.

Contractor: Broccolini Construction

Architect: Rubin & Rotman associates

Landscaping engineer: Beaupré et associés

Civil engineer: Groupe Teknika

Structural engineer: BCA Consultants

Mechanical/Electrical engineer: PMA et associés

Commissioning: Martin Roy et associés

 
© La Maîtrise de l’énergie – SEPTEMBER 2009

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