Alexander Street Community - 111 Princess Ave

The building is comprised of a 10-storey tower along Princess Avenue with 100 units of permanent supportive housing, and a 7-storey tower intersecting at 90 degrees along Alexander Street with 39 transitional housing units. Each suite contains a bathroom, small kitchen and living space, with a rough square foot area between 250 and 500 sft. The building contains a secure lobby, multi-purpose spaces, dining room, gym/spa/salon, lounge and offices, as well as common laundry rooms, bike storage and a bedbug treatment room. There are also two accessible rooftop terraces with space for residential gardening. The total building area is 7,482 m2.

Amenities located on the ground floor include places where tenants can receive education, training and links to community health services. There are community kitchens for nutritional information and basic meal preparation.

Sustainable Sites

Negotiations with the City resulted in an allowance to provide only one parking space per 10 dwelling units, for a parking requirement reduction of 88%. Of the 13 total parking spaces, three spaces have been set up to accommodate alternative fuel vehicle (AFV) refueling.

This project has ample bicycle parking spaces, with a total of 112 spaces in the building located in 3 bike rooms off the ground floor, and additional bike parking on the 2nd floor.

Parking is tucked underground to prevent the heating up of a mass of asphalt, known to create a heat island effect, which negatively impacts microclimates and habitat.

Vegetation and highly reflective pavers were other key strategies to prevent a heat island. An intensive green roof (299 m2) was designed and installed on the project. Combined with ground level plantings, a total of 22% of the project’s area was restored to vegetation, with the layout of the roof also incorporating high albedo pavers.

For a more hardy and drought resistant landscape, native and adaptive species were planted. On site, you can see Coral Bark Maple, Katsure, Pink Kousa Dogwood and Star Magnolia trees, with blue fescue and yellow Rockrose for perennial groundcovers. These plantings meet both LEED and City of Vancouver requirements.

Materials & Resources

This building was designed to be a durable building with a design life of 60-to-100 years. Care and inspections were made to ensure the building envelope construction conformed to the design details.

Over 15 % for the value of the project’s building materials come from recycled sources with the contractor working with sub-trades to keep this documented and tracked. Much of the drywall, steel frames, metal doors as well as the bike racks and lockers were manufactured from recycled materials.

During construction, efforts were made to ensure waste materials were separated in order to be recycled after leaving the site, leading to a waste diversion rate of approximately 80%.

Energy

The design team sought energy savings in their systems designs wherever possible. Energy consumed for heating and cooling was reduced through the use of a high efficiency Aermec heating system, heat recovery units in the ventilation system, and a solar hot water array.

Process water for radiant heating and domestic water is preheated by a solar hot water array and supplemented by the high efficiency boiler.

Passive design strategies, such as passive solar heating and natural ventilation, supplement the HVAC systems.

The building heating and cooling loops are connected through individual dedicated air source heat pumps. The building heating water loop has supply and return water pipes that are connected to radiant floor heating within the suites and running to force-flow heaters and fan coil units at amenity and office areas.

The heating loop is circulated with two, variable speed pumps, each with a Variable Frequency Drive (VFD). A Variable Frequency Drive (VFD) in the central air handling system reduces energy use. The heating loop flow is controlled pressure differential, with the VFD modulating pump speed to achieve the prescribed differential pressure in the loop. This reduces the amount of pumping energy consumed.

Radiant Heating

Individual living units have been provided with radiant slab heating. Pipes installed in the bottom of the concrete slab and low temperature heating water is circulated through the piping in the slab to provide radiant heating. This provides a comfortable heat that keeps occupants warm without overheating the air.

Solar Hot Water Heating

The solar hot water heating system was designed to be able to generate 5% of the building’s energy requirements. A number of solar panel collectors on the roof are connected to the building heating water system. Solar collectors provide ‘first stage’ heating for the building’s heating loop through a heat exchanger, which is tied into the building heating water loop. The heat exchanger is a small ‘double wall plate and frame’ type, which makes it an easily maintained system with little to no heat loss, and little chance of fouling or intermixing of fluids.

Heating for the high temperature water-heating loop is fed from the solar water heating system first, followed by the air source heat pump. The solar heating and air-to-water heat pumps are supplemented as needed by a high-efficiency condensing type boiler complete with a primary heating water pump to reduce standing losses when boiler is not in operation. The use of solar and air-source heat pump (ASHP) reduces energy and fossil fuel use for the building, which also reduce greenhouse gas emissions.

Heat Recovery

Heat recovery is a heating, cooling and ventilation strategy that saves energy. Return air from each of the suite bathrooms is drawn back into the air-handling unit to mix with incoming outside air, or relieved directly outdoors. Exhaust air gets drawn through a heat wheel at the central air-handling unit in order to recover this heat that would normally escape a conventional building. A heat recovery system through an air-to-air heat wheel is also provided to pre-heat outside air in colder weather. If the building is in need of heating, building relief air is directed through the heat wheel. If the building does not require heating, the air goes through bypass dampers to the outdoors. A pressure sensor controls variable speed fans within the air-handling unit if the system is in heat recovery mode.

In areas with operable windows, such as the suites and offices, the occupant can utilize natural ventilation for their personal thermal comfort.

Occupancy Sensors

Automatic controls can be excellent energy savers as well as benefit indoor environmental quality. Occupancy sensors in common amenity and group areas cut back supply air volumes when these areas are not in use, thereby reducing energy. These areas revert to a reduced ‘day set point’ and are energized once there has been several minutes of occupant activity in the space. Occupancy sensors are dual sensing type and are also used to control the lighting systems, with manual switches where needed. Exterior lighting is controlled with time clock/photocell sensors.

Efficiency through Automation

The temperatures throughout the building is controlled by the Building Management System (BMS) consisting of direct digital control (DDC), with temperature sensors provided in each zone and zone controls. DDC systems allow building managers to observe and change temperatures or schedules for systems in the building directly from a computer, which can save significant time and money and are much more efficient than conventional thermostats.

Maintenance Requirements

The building was designed and constructed with maintainability at the forefront. The building’s mechanical and electrical systems had to be simple to use, easy to maintain and equipped with labeled isolation valves. Likewise, it was important that residents were well educated about uncommon green building features such as radiant heating to avoid any perception that the systems were working incorrectly if not used correctly.

Indoor Air Quality

Good air quality was ensured before occupancy by flushing the building with outdoor air or completing an indoor air quality test. A carbon monoxide (CO) monitoring system must be used to ensure occupant comfort and safety.

The heating and ventilation systems help to meet proper and healthy thermal environmental and ventilation conditions, with zone temperatures and air change rates conforming to ASHRAE standards 55 (2004) and 62 (1989).

Ample daylight and access to views in regularly occupied spaces stimulate the brain, reduces stress and may increase productivity, all of which enhance the building’s working and living environment. Tapping into natural light as a resource also cuts electrical energy use.

Overall, this project sought to keep a balance between high performance, low-impact design with durability and ease of maintenance for an overall livable building for its occupants.

Sources: Inland Technical Services