The Vital Signs Project: Green on the Grand Case Study

Green on the Grand

Kitchener, Ontario, Canada

Hypothesis 1: Energy Reduction

Hypothesis 1: A significant energy reduction through the successful use of advanced envelope construction and mechanical systems without affecting the occupant attitude or the quality of the work environment.

The designers objectives were to achieve a building that minimized the embodied energy, was built with materials that contained no CFCs or HCFCs and would significantly reduce waste during construction. In addition, the designers hoped to achieve a 40% reduction in total energy and water required to operate the building, as compared to a traditional commercial building of similar size built to ASHRAE 90.1 standards. These aggressive design objectives were structured to reduce energy, without changing the occupant attitude. Occupant survey results, building methods, and mechanical systems are the main focus, however site planning, building massing, building plan, and building openings are considered in determining the success of these objectives.

Building Envelope

Green on the Grand uses a structural support system of wood. This reduces the cost and minimizes the embodied energy of the building (the energy required to grow, harvest, extract, manufacture, or otherwise produce a building product) and allows for more insulation and less thermal bridging at floor intersections, as compared to steel-stud construction. To improve the durability of the structure and dimensional stability, engineered wood products, such as laminated strand lumber (LSL) and laminated veneer lumber (LVL) were chosen. An exterior insulated finishing system (EIFS) adds to the thermal performance of the building.

The wall cavities are filled with blown-in cellulose insulation made from 100% recycled newspapers, 216 mm (8.5 inches) for the first-storey walls and 140 mm (5.5 inches) for the second-storey walls. A 6-mil polyethylene vapor barrier is attached to the inner surface of the wall assembly.

The exterior of the wall is covered with 50 mm (2.0 inches) of expanded polystyrene insulation (EXPS) that is coated with stucco to provide a finish. This EIFS provides a layer of insulation over all studs and other thermal bridges. EIFS, however, are not durable systems. They are extremely susceptible to damage at ground level. This type of system is also very susceptible to moisture penetration. Once cracking has occurred on the outer stucco layer, water has a path to the interior cellulose insulation and oriented strand board (OSB). Maintenance of this wall type is very important.

In addition, the underside of the slab-on-grade first floor is insulated with 50 mm (2.0 inches) EXPS to reduce heat loss and improve thermal comfort. The basement walls are covered with a polyethylene sheet for waterproofing; this eliminates the use of tar, a source of soil contamination. 75 mm (3.0 inches) of rigid fiberglass is both a drainage layer and insulation.

The roof at Green on the Grand has sections that are steeply pitched and sections that are shallow in pitch. Steeply pitched sections are constructed from 450-mm (17.7 inch) wood I-joists, while pre-manufactured wood trusses support shallow pitched areas. The roof is finished with high-grade, fiberglass-reinforced shingles for a long life expectancy.

Heat Recovery and Ventilation

Green on the Grand offers all of its occupants 100% fresh outdoor air. The air is first heated or cooled and then vented through the building.

The ventilation system is independent of the heating and cooling system. The main components of the ventilation system are two heat exchangers, two fans, and a heating/cooling coil. This unit provides a continuous flow of air at a comfortable temperature and humidity. The fresh air is circulated via a displacement system, reducing fan energy.

Water Conservation

The Green on the Grand set a design objective for a reduction in water consumption of 30% as compared to a typical office building. This objective is obtained through the use of collected rainwater for landscape watering; the elimination of a cooling tower; and the use of low water-consumption bathroom fixtures and dishwashers.

Table 1 : Annual Water Use

Units in m³/person (cubic yards/person)

Finishes and Furnishings

Finishing and furnishings have a great influence on the indoor air quality of the office space. In Green on the Grand the interior walls are 100% recycled gypsum board; all walls are painted with VOC-free paints; and flooring is of natural linoleum. Natural linoleum, while slightly more expensive, is significantly lower in embodied energy than carpet. The furnishings are made of particleboard that is free of formaldehyde, or reused and refinished.

Heating and Cooling

The philosophy of the Green on the Grand design was to create a building as energy efficient as possible, and as environmentally friendly as possible. Natural gas is used as the fuel for the system and is therefore CFC/HCFC free.

Space heating and cooling is provided through water-based radiators located in each tenant area. Radiant heating and cooling offers three main advantages over traditional forced-air heating.

• It uses less motor energy.
• Water is a more efficient heat transfer medium than air.
• More even and comfortable warmth can be provided with more effective zonal control.

Conventional finned radiators would not be able to meet the building cooling load, so a new system was required. Ceiling panels are used. The panels are painted the same color as the ceiling. So, although they cover 30% of the ceiling area, they are unobtrusive. It is important to note that, dehumidifying ventilation prevents condensation from forming on the cooling panels.

The radiators carry hot water in the winter and cold water in the summer. The water is both heated and cooled by the same efficient appliance: a natural gas fired boiler/absorption-chiller.

Green on the Grand uses natural evaporative cooling to cool the building occupants. Any air conditioning system requires a method for rejecting heat to the outside. Normally, cooling towers are used for this purpose using large amounts of water and fan energy. The Green on the Grand building, however, uses a manmade pond located in front of the building. The pond is approximately 20 meters x 10 meters (65.62 feet x 32.81 feet) and is an average of 0.9 m (3.0 feet) deep. When the chiller is operating, untreated pond water is filtered and circulated through the chiller condenser. The hot water is then ejected into the pond for evaporation and cooling.

Energy Simulation

Since actual operating costs were not obtained, results from an energy simulation were used to determine the effectiveness of the energy and water consumption targets. The total energy costs were estimated to be 425 of a typical new office building. This includes space heating and cooling, water heating, lighting and electrical demand, pumps & fans, and water and sewer costs.

Occupant Survey

The results of the occupant survey indicated that 80 5 of occupants were satisfied with the lighting and less than 20% found a problem with glare in their work environment. 40% indicated that good ventilation was one of the most important features in a work place but only 50 % were satisfied with the ventilation in this building. This was attributed to a lack of air conditioning in the summer as several comments were made about this.

Discussion

The interior ducting and piping was very problematic. There is the issue of passing ducts and pipes through fire separations (a building code requirement, which is more frequent in wood framing).

Both the hydronic heating/cooling system and the low-velocity fresh air system proposed duct problems and created aesthetic issues.

There is no ambient noise in the building, because both the hydronic and fresh air system are silent. Therefore there is a noise problem from the second floor to the first, even though there is acoustic tile, gycrete, and flooring.

Thirty percent of the tenants indicated a general dissatisfaction with the ventilation system and the ambient temperature. However, twenty-five percent were satisfied with the system. General comments from the occupant survey are that people would like more control over the temperature in their individual offices, and more operable windows but are happy with the lighting and ventilation through the winter months.

From the data collected by the HOBOs, which were located throughout the study area it was found that indoor temperatures were within the comfort zone during office hours. Outdoor temperatures during this time were representative of a mild winter.