Humber Arboretum Centre For Urban Ecology

By Taylor Hazell architects with Architects' alliance

Left: Engineered landscape walls with concrete retaining structures. Right: The Thermal Chimney. Photos: Tom Arban Photography

Project Name: Humber Arboretum Centre for Urban Ecology

Project Owners: Humber College Institute of Technology and Advanced Learning, City of Toronto, and Toronto and Region Conservation Authority

Project Location: 205 Humber College Boulevard, Toronto, ON, Canada M9W 5L7

Architects: Taylor Hazell Architects with architectsAlliance and gh3 (landscape architects)

Project Completion Date: October 2007

Project Site: Previously Developed Land

Project Type: Higher Education, Interpretive Centre, Campus

Project Type Context/Setting: Suburban

Other Building Description: New

Site Area: 27,800 m2

Building Gross Floor Area: 448 m2 / 5,000 sq ft

The Humber Arboretum Centre for Urban Ecology, funded jointly by the Humber Institute of Technology and Advanced Learning, City of Toronto, and the Toronto and Region Conservation Authority, provides indoor and outdoor environmental education to schools and to the public for all age levels. All three funding partners desired an assertive, modern, green building that was a signal of change in values toward sustainable development and energy conservation; in that service, it combines materials and forms that represent ideas that can be easily incorporated into future institutional, commercial and residential building design.

Used primarily by school-age children, including those as young as three years old, the architectural and engineering messages had to be clear and memorable, thus the design team focused on high and low tech systems that are most likely to be used in design in the next decade. Set on the edge of the Humber Ravine in a highly sensitive natural area, the combination of new architecture and man-made landscape showcases the way that technology can assist in the preservation of the natural world. The Centre for Urban Ecology is, in essence, a living laboratory.

The project had a limited budget and was built on a difficult-to-access site for a cost of Cdn $3.4 Million. Corporate donors were attracted to the project by the use of ideas promoting their own core values. Through shared investment, an opportunity for business development and education was created. As one of the first LEED™ Gold buildings in Toronto, the Humber Arboretum Centre for Urban Ecology has strengthened the branding of all involved as supporters of the sustainable city.

Lower level project room with view to the outdoor classroom. Photo: Tom Arban Photoraphy

This project is a demonstration of the imperative to create places where landscape and architecture come together. In essence, the building was designed to have a modest footprint on the landscape, respecting its proximity to the sensitive Humber Valley and the mature plantings and landforms of the Arboretum surrounding it.

The two- storey building is wrapped by an earthen wall on three sides and the landscape falls away on the west to create a sheltered outdoor classroom. The building is otherwise characterized by transparency and lightness. It is a glazed box set into a hill with its main space acting as a lookout, where teaching occurs against the backdrop of the landscape. Wildlife including deer, fox and many species of birds can be seen from the classrooms with the changing seasons. The teaching extends out into the arboretum where students experience changes in natural colour, temperature and sound that showcase the rhythms and chronicity of the seasons in this natural setting.

The earthen wall was designed as a landscape element and thermal buffer. Other key energy conservation strategies include the approach to natural ventilation, access to natural light through high performance glazing, site treatment of waste, passive heating and cooling. These straightforward messages combining high and low tech systems, demonstrates the range of techniques in construction that are available in urban environments. The opportunity of designing a structure that was meant to celebrate a sustainable future led to architectural ideas that could be explored in a direct and emblematic way. The metaphoric ideas of “bridge”, “beacon”, “embedded landscape”, and “outdoor prospect” are manifest in the walk through the designed landscape, the siting of the building on a promontory, the pavilion form, and the prominence of the thermal chimney and central stair. The need to maintain a small footprint, and flexible space on a tight budget, led to openness and reliance on the landscape to colour the architecture.

The foundation system for the building and retaining walls were chosen for minimum disruption to the land. The building caisson foundations permitted founding on existing unconsolidated fill that would have to have been removed with conventional solutions. Footings for the earthen wall and concrete retaining walls utilized “rammed aggregate piles” to consolidate the loose fill. Again, less impact through the soil significantly reduces soil removal and minimal impact to other dynamics in the existing terrain.

Lower level project room with view to the outdoor classroom. Photo: Tom Arban Photoraphy

Upper level classroom. Photo: Tom Arban Photography

Situated on the edge of a ravine, at Humber Arboretum, adjacent to Humber College’s North campus, the Centre for Urban Ecology replaces the Humber Arboretum’s “nature centre” designed by Jerome Markson over 30 years ago; a wood structure that has been outgrown by the needs of the staff, and had been progressively damaged and worn over its lifetime.Community building around a sustainable agenda was the focus of the Humber, TRCA, and City partners. The Humber Arboretum neighbourhood is primarily composed of 1960’s era mid and high-rise housing.

The Humber Arboretum provides an open and natural place for residents in this neighbourhood, and surrounding priority neighbourhoods, who would not otherwise have access to green space. This has enabled the college to reach out to its neighbours to provide service and education in a way that had not previously been imagined.The project team realized that, “It’s very difficult for urban kids and we know about that particular group of kids, who come from apartment buildings - to engage with the outdoors.” Community education goals have been exceeded for day and summer school programs.

A variety of public programs that run all week, including evenings and weekends, attract visitors and students of all ages.The Centre is served by 5 municipal and regional bus routes with vehicle parking within existing grounds 250 metres from the site. Accessible parking and school bus drop off are located at the entry to the garden. Barrier free and bicycle pathways promote the value of outdoor recreational and contemplative activities.

Map of the Humber Arboretum Centre for Urban Ecology site and environs. Image: THA Inc.

Metrics

Percentage of building population using transit options other than single occupancy vehicle: 85%

Number of parking spaces per person (occupants & visitors): 1:4.6

Percentage of building population traveling to site by public transit, carpool, bicycle, or foot: over 85%

*please note that the above figures are for the entirety of Humber College Institute of Technology and Advanced Learning North Campus with which the Centre’s figures are currently integrated.

Site plan. Image: THA

The Centre preserves an important open space in an otherwise urban landscape. The vegetation, including that chosen for the green roof, responds to the need to use native and appropriate species. Retaining walls around the edges of the site utilize an earthwork and pile system that has been planted on its sloped sides, and which protects the ravine edge. The outdoor classroom is planted with river birch that will grow to shade the west wall of the building. This modern landscape design contrasts with planting at the arboretum. The design intent was to integrate the architecture and landscape experience and to emphasize their mutual reliance in the sustainable future.

A new ground-breaking international accreditation system known as the Sustainable Sites Initiative (TM) [SITES(TM)] is being developed, and the Centre for Urban Ecology has been selected as one of the test sites for this new accreditation. The Centre will act as a pilot project to determine the requirements for acceptance as a qualifying site in this new rating system for green landscape design, construction and maintenance.Guiding principles for the ongoing SITES sustainable landscape design, installation and maintenance program follow United Nations protocols for sustainable development using an ecosystem services framework. Some of the specific ecosystems services being targeted for support and benchmarking in and around the Humber ArboretumCentre for Urban Ecology site include climate regulation, erosion control, pollution remediation, protection of water resources, food production, biodiversity protection, pollination services, and human health & well being. Underlying principles include design with nature and culture, precaution, support for regenerative and living systems, using a collaborative approach, and integrity in leadership and research.

More Information on the Sustainable Sites Initiative

In addition to the pilot studies ongoing for Sustainable Sites Initiative, the Centre for Urban Ecology is also fulfilling its mandate toward leadership in green facilities management and community education by taking part in the creation and pilot of the Ontario EcoCentres accreditation program. Ontario EcoCentres is a new benchmarking and certification program that provides guidelines for green management to museums, zoos, environmental education facilities, and other learning centres.

Metrics for the EcoCentres system include:

occupancy behaviour, performance management, resource conservation, curriculum learning programs, environmental quality, procurement, professional development, biodiversity, transportation, social equity and carbon neutrality.

Summer cooling diagram, illustrating the solar chimney working in concert with the automated windows to release hot air and bring in cool air. Image: THA

The building orientation maximizes solar gain for winter heating. Exposed concrete floors and walls provide thermal storage to moderate temperature swings throughout the year. A brise soleil overhang above the south elevation, and deciduous plantings around the south west corner, limit solar gain in the summer. Green roof planting also reduces summer heat gain and provides useful small scale retention and filtration of roof runoff draining to the rain cistern. Automated windows in the glass facade provides free cooling in the spring and fall, and natural ventilation during the summer. The natural ventilation is assisted by heat recovery ventilators, and fans automated by thermostatic controls and outside temperature.

Summer cooling diagram, illustrating the solar chimney working in concert with the automated windows to release hot air and bring in cool air. Image: THA

View of the east façade, showing the brise soleil, the solar chimney, and the iconic red door. Photo: Tom Arban Photography

High performance triple glazing of walls on all exposed sides provides tremendous natural day lighting and excellent energy efficiency. Low emmissivity coatings limit solar gain on glass within the triple glazed walls. The light achieves 90% exposure to the building area, with electric light either off, or dimmed, during most days. The building is ventilated by a hybrid system of HRV’s, operable windows, and the thermal chimney. A monitored BAS System controls the operation of the integrated ventilation systems. Indoor air quality and comfort were key design objectives: the building utilizes CO2 monitoring, occupant control of heating and air handling systems, and materials with low VOC emissions.

1 Engineered landscape wall/ sierra system 2 Terrace 3 Rainwater harvesting tank 4 Biofilter discharge 5 Triple-glazed wall 6 Lower green roof 7 Thermal chimney 8 Radiant heat in concrete slab 9 Brise soleil

Water reduction and solid waste-management diagram. Image: THA

The goal was to use as little city water as possible and to treat all wastewater on-site, using the best available technology. This was achieved by integrating water capture, water treatment, and water conserving systems. Harvested rainwater from a cistern supplies water for an outside hose bib.

The design achieves an 86% reduction in irrigation water by using drought-resistant species and a drip irrigation system for trees; native grasses do not require watering, nor do plants used for the green roof. Low flow fixtures reduce water use by 35% (dual flush toilets; low flow urinals; low flow bathroom faucets; low flow kitchen faucets). Sanitary sewage is treated on site by means of the Waterloo Biofilter treatment system, removing over 50% of total nitrogen and reducing BOD and suspended solids to less than 10ppm. Treated effluent is disposed of on site through shallow buried trenches in the root zone of the Arboretum trees and shrubs. This also reduces the wastewater treatment burden from the municipal utility.

Statistic provided by Enermodal Engineering Ltd. Image: THA

By careful planning and selection of equipment, the water and wastewater treatment systems were integrated into the site with minimal impact.

Metrics:

Precipitation managed on site: 100% Total water used indoors: 123,000 L/yr vs base line of 188,000 L/yr Total water used outdoors: 144,000 L/yr

Percentage of water from reclaimed sources: 100% of irrigation

Percent wastewater reused on site: 100%

Upper level glass walls surrounded by earthen wall. Photo: Tom Arban Photography

The sustainability measures used in the centre have reduced annual energy costs by 61%.Central to the design was the coordination between architects and engineers that developed primary approaches to siting. The earth mass that surrounds the building moderates temperature gains and losses in summer and winter respectively. Oriented to allow light penetration and gain solar heat in the winter, trees to the south and west shield the building in summer. Losing their leaves in winter; they allow sunlight to filter through the landscape to heat the building. Concrete floors act as heat sinks where heat is retained for use in the winter, and shed during the nighttime cooling cycle in the summer. The absence of air conditioning reduces energy demand significantly and promotes a more intuitive natural ventilation system throughout the year.Other measures include a well-insulated building envelope; high performance windows; energy efficient lighting controlled by occupancy sensors; energy recovery ventilation system; ventilation air controlled by monitored CO2 levels; energy efficient mechanical equipment. 80% of the roof is planted with native sedum, reducing the urban heat island effect. The roof plantings also serve to reduce interior building temperatures in the summer.

Metrics:

Percent total energy saving: 61% of annual energy costs.

Energy Intensity: 388 kWh/sq m-yr vs base case 1136 kWh/sq m-yr

Total Energy: 303,000 MJ/yr vs 888,00 MJ/yr

Electricity: 98,600 MJ/yr vs 175,000 MJ/yr

Panoramic views surround the upper classroom. Photo: Tom Arban Photography

Reuse and recycling of construction materials resulted in an 87% diversion of construction waste with separate bins for steel, concrete, wood, plastic, gypsum, and cardboard. Recycled building materials within the building account for 11% of the total by cost. Insulation, concrete, gypsum board, structural steel, steel decking, medium density fibreboard, and carpeting are made from recycled material. To reduce energy expended in transporting materials, regional sourced materials were given preference. These materials represent over 24% of total by cost, and include concrete components, insulation, structural steel, gypsum board, steel studs and decking, paving stones, gravel. In-house recycling is located within the Centre and materials are sorted before being picked up for delivery to recycling centres. Currently, the Centre has on-site composting for green waste, as well as worm composting indoors, and is working towards 100% composting on site.

Foundation systems for the building and earthen wall, and concrete retaining walls, were chosen to drastically reduce the disruption caused by the excavation associated with more typical construction methods. Piles and “rammed aggregate piers” consolidated loose fill that would otherwise have to have been replaced to develop adequate bearing.

Construction Waste Diversion - percentage of materials by weight. Statistics provided by Enermodal Engineering

Biofilter installation on site, during construction of the Humber Arboretum Centre for Urban Ecology. Photo: THA

Above: brise soleil and earthen wall. Photo: Tom Arban Photography

High quality and durable materials were used to ensure that materials were not easily damaged through public use. Humber’s maintenance practices were researched to ensure that the chosen materials would comply with service agreements. There was as emphasis on standardization of products so that they could be easily replaced, should any one area of failure occur.

The material palette was simple and durable: exposed, polished high fly ash concrete for floors and stairs; veneer faced MDF operable panels, doors and millwork; glass for exterior walls; painted gypsum board for ceiling and walls.Flexibility of use was a hallmark of the planning, as the facility had to be used by two groups of 30 students at any given time time (upstairs and downstairs classrooms). The interiors are spacious and versatile, so that furnishings and displays can be changed easily, and that open spaces are easily cleaned after workshop activities.

The simplicity, clarity and generosity of interior spaces and their intimate relationship to the landscape make this building highly adaptable as an event space, gallery or museum.

Brise soleil shades the classroom. Photo: Tom Arban Photography

The anticipation of participating in the design process for a sustainable building evoked a full range of solutions and wish lists from the stakeholders. One of the architects primary roles at the beginning of the project was to work through the sustainable agenda to focus on a number of key aspects of building design and operation that suited the budget, program and maintenance routine of the occupants. Once this was established, a joint committee of stakeholders ratified a list of images, systems and building principles that would work into the design stages. Community building around a sustainable agenda became a focus of the committee.The outcome is a learning environment where landscape stewardship, ecological regeneration and wise use of resources are at the centre of the curriculum.

Visitor inspects the engineered wall. Photo: Tom Arban Photography