VanDusen Botanical Garden Visitor Centre - Net-zero building designed to meet the Living Building Challenge system

Founded in 1971 and located five kilometres from downtown Vancouver, the VanDusen Botanical Garden preserves an important 22-hectare environmental oasis within
an increasingly dense urban context.

By Jim Huffman


Inspired by a native orchid, the design for the Garden’s new Visitor Centre considers the complete system of environmental technologies - how the building operates, what it’s made of, and the nature and ecological systems around it, and tries to create a situation where the building becomes a positive factor in all of those things.

With solid walls that protect visitors from the busy street and transparent walls that open the building toward the garden, the 1,810m2 Visitor Centre houses a café, library, volunteer facilities, garden shop, offices and flexible classroom/rental spaces. The project is targeting both LEED Platinum certification and recognition under the Living Building Challenge [LBC]. LBC recognition will require the project to demonstrate net-zero energy and net-zero water consumption along with other stringent performance prerequisites.

SITE ECOLOGY
Through mapping and analyzing the garden’s ecology, the project team was able to integrate natural and human systems, restoring biodiversity and ecological balance to the site. The green roof and surrounding landscape, named the Cascadia Garden, were carefully designed to include native plants, forming a series of distinct ecological zones; a vegetated land ramp was included to connect the roof to the ground plane, encouraging use by local fauna; and old-growth trees were carefully preserved, facilitating an ecologically balanced system of wetlands, rain gardens and streams.

NET-ZERO WATER
The Visitor Centre employs a number of water conservation and treatment strategies. Rainwater is captured on the green roof, which also acts to control excess rainwater runoff. This rainwater is then filtered and stored in a 300,000-litre custom cistern built into the land ramp of the eastern most roof petal.

Along with filtered greywater from sinks, the filtered rainwater is used for flushing toilets. Waterless urinals also serve to minimize water consumption. 100% of blackwater is treated by an on-site bioreactor - the first of its kind in Vancouver - which is located underground to the north of the building. Treated blackwater is then released into a new feature percolation field and garden.
The City of Vancouver’s requirement that all potable water be chlorinated, meant that the building had to be connected to the municipal supply. Because chlorine is a ‘red list’ chemical under LBC, this required the design team to apply for an exemption for the Materials petal.

NET-ZERO ENERGY
The Visitor Centre uses on-site, renewable sources of energy  - over 50 geothermal boreholes, solar photovoltaics, solar hot water tubes - to achieve net-zero energy on an annual basis, another requirement of the Living Building Challenge.
A solar photovoltaic array, located in the parking lot, provides 11 KW of power to the facility. Located on the roof of an adjacent existing building, 400 solar hot water tubes heat hot water, which is stored in geoexchange boreholes at the building’s north end. This energy is used for heating the building’s water and for heating or cooling needs, depending on the season.

Passive design strategies that promote energy efficiency were also incorporated: green roofs that insulate the building; the oculus which facilitates air circulation to cool the building; and wide roof overhangs that prevent heat gain while also providing rain protection. The inclusion of a heat recovery unit maximizes the benefits from the return air, which is naturally warmed and captured from the oculus or from the thermal mass of walls.

Through transferring excess heat energy to nearby Shaughnessy Restaurant, the Visitor Centre obtains an equivalent amount of hydro-electric generated electricity from the grid. By exchanging surplus heat energy for electricity from the grid, the Visitor Centre achieves net zero energy on an annual basis and also carbon neutrality.

MATERIALS
The most difficult Living Building Challenge requirement to achieve is the Materials Imperative, which calls for avoiding items on the Red List, a list of substances that cannot be used in projects because they have been determined to be detrimental to human health and the environment. The Challenge also mandates the use of only FSC-certified wood products for any non-reclaimed wood, a very high minimum threshold for recycled content, and a series of proximity thresholds that require materials to be supplied locally/regionally, limiting long-distance transport.

To this end—and to provide a beautiful and warm environment—the Visitor Centre uses wood products extensively, from the panelized roof structure to the cladding, furnishings, millwork and wall finishes. The use of wood contributes to the project goal of meeting the Challenge requirements because of the material’s sequestered carbon.
Both LEED and LBC require 12 months of in-service operational data to evaluate building performance. The project team made the decision to run the systems for a full year to maximize its efficiencies  prior to commencing the data collection period. As a result, the performance data presented with this article is based on design projections rather than in-service observations.

MATERIALS

  • - Rammed earth sidings
  • - Vegetated roof by Zinco Canada
  • - Prefab glued-laminated beam roof system
  • - On-site bio-reactor waste water system
  • - Building uses natural ventilation, and has only one heat recovery ventilator [HRV] to reclaim heat from exhaust duct. Solar and geothermal energy used to heat water, and radiant floor slab heating is provided throughout. [Courtesy Trotter & Morton Building Technologies Inc.].

PROJECT CREDITS

  • Owner Vancouver Board of Parks and Recreation
  • Architect Perkins+Will [formerly Busby Perkins+Will]
  • General Contracto r  Ledcor Construction
  • Structural Engineer Fast + Epp
  • Mechanical/Electrical Engineer Integral Group [Cobalt Engineering]
  • Civil Engineer R.F. Binnie & Associate
  • Code Consultant B.R. Thorson Ltd.
  • Cost Consultant BTY Group
  • Envelope Consultant Morrison Hershfield
  • Landscape Architect Sharp & Diamond Landscape Architecture Inc. with Cornelia Hahn Oberlander
  • Lighting Design Total Lighting Solutions
  • E cology Consultant Raincoast Applied Ecology
  • Acoustical Consultant BKL Consultants
  • Commissioning Agent KD Engineering
  • Commissioning Authority KD Engineering Co.
  • P hotos Nick Lehoux

PROJECT PERFORMANCE

  • - Energy intensity [building and process energy] = 400MJ/m2/year
  • - Net energy intensity [taking into account onsite renewables] = 284MJ/m2/year
  • - Energy intensity reduction relative to reference building under ASHRAE 90.1 - 1999 = 67%
  • - Potable water consumption from municipal sources = 192L/m2/year. [Note: Because of large seasonal v ariations in occupant load litres/occupant was not calculated]
  • - Potable water consumption reduction relative to reference buildin g = 60.1%
    - Regional materials [800km radius] by value = 30%
    - Reclaimed and recycled materials by value = 10 %

Jim Huffman, Architect AIBC, AAA, LEED AP is Associate Principal with Perkins+Will in Vancouver.

Print this article | Send by e-mail

Leave a Reply