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Net Zero

VISION + CONCEPT Cheap Jerseys china

DESIGN A BUILDING THAT GENERATES AS MUCH ENERGY AS IT CONSUMES ON AN ANNUAL BASIS

That was the goal for the SEFC Net Zero building, a focal point of sustainable design at SEFC and Canada’s first Net Zero multi-unit residential building. The ambition to build a Net Zero building emerged in 2006 from the City of Vancouver’s Sustainability Group. “At that time, the idea of doing something that was carbon neutral was really out there,” says David Ramslie, the City’s Sustainable Development Program Manager.

The City targeted one of the affordable housing buildings, an eight-storey seniors’ residence with 67 units, including 6 street-level townhouses, to be the Net Zero building. “With this building, the City wanted to go above and beyond, and see what could be accomplished. LEED™ Gold was impressive, but we knew that Net Zero would be the next generation of green building. This approach was new and could be significant – this would be our showcase piece,” says Ramslie.

The project was supported by Canada Mortgage and Housing Corporation (CMHC), who spearheaded the initial design charette for the building. “The SEFC Net Zero Building demonstrates the application of sustainability principles at the multi-unit scale, which is particularly important given that multi-unit buildings account for an increasing share of new construction in Vancouver and cities across the country,” says Lance Jakubec, Senior Consultant at CMHC.

“This project – a multi-unit residential Net Zero building – was a North American first. This presented an added challenge, as there was not a lot of experience to draw upon,” says Esteban Undurraga, co-founder and former partner at Recollective Consulting, the green design consultant on the project. “What’s more, the design was already addressing a multi-stakeholder set of objectives: the City of Vancouver’s green building and community plan, Olympic venue requirements, BC Housing’s standards, LEED™ Gold rating and the developer’s business feasibility.

“In the face of all these challenges, the City’s constant support was key to developing this new professional capacity: accepting mistakes, exploring options, making timely decisions and moving forward,” says Undurraga.

Model with Net Zero building. Credit: City of Vancouver

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BUZZWORD: Net Zero

The SEFC Net Zero building generates as much energy as it consumes over the course of a year. Buildings account for about one-third of Vancouver’s energy consumption. Much of the energy we use is derived from fossil fuels, which, when burned, release greenhouse gases (GHGs) into the environment. Therefore, reducing our energy use and seeking greener options is one of our biggest sustainability challenges. Net Zero building is a step toward GHG-neutral (or carbon neutral) low-impact building design.

“ We knew Net Zero was the next generation of green building”
David Ramslie, Sustainable Development Program Manager, City of Vancouver

Net Zero Design: The Business Case

There’s no formula for reaching Net Zero, and, in the case of the SEFC building, there was no precedent to follow. With all of the constraints associated with the project – schedule, budget, physical site limitations, stakeholder conditions and the required level of innovation – the design team had to build a solid case if they were to be able to realize the Net Zero target. “One word: resourcefulness,” says Albert Bicol, a mechanical consultant with Cobalt Engineering. “The more resourceful you are, the more success you will have in a project like this.” By examining the building in its specific context, the team looked for an appropriate strategy for achieving Net Zero. As it happened, the perceived constraints of the project – the building’s dense urban context – became the vehicle to reaching the annual energy balance. “What we learned from the process is that the success of this building was contingent upon the relationships between it and its neighbours. The Net Zero aspiration would not have been attainable without the ability to take advantage of connections to other buildings,” says Undurraga.

“People associate the Net Zero concept with off-grid living. The pastoral image of a carbon neutral building out on its own in a field – like a spaceship – is not what this project is about,” says Ramslie. “It’s true that it takes a village. Trading energy between buildings, and integrating systems, is how we are able to meet the Net Zero goal.”

Northern elevation view including the Net Zero building (second from left). Credit: Walter Hardwick, 2007

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DESIGN APPROACH

The team had their work cut out for them. By the time the City made a commitment to the Net Zero target, much of the programming for the building had already been determined. “The building was already massed, the site chosen, the proportions already set. Within this context, it was up to the design team to explore how to tweak the form to maximize energy efficiency and how to generate energy onsite,” says Ramslie. “It became clear early on that technology alone would not get us there. Getting there would require an integrated approach.” gBL Architects was responsible for the design of the Net Zero building.

“The building was designed around a lot of opportunities for passive design,” says Stu Lyon, Principal at gBL Architects. “We implemented a significant amount of passive strategies that will affect livability, maximize daylight and natural ventilation and eliminate the need for air conditioning.” These strategies were instrumental to lowering the building’s energy demand.

The team considered a number of potential layouts for the residential units, with a view to improved comfort and energy efficiency. “We had to maximize cross-ventilation and daylighting from two sides. The typical floor plan for the building evolved around creating as many – if not all – suites either on a corner or with two sides. To achieve this, we eliminated the concept of the interior corridor and put both the corridors and the stairs on the outside perimeter of the building,” says Lyon. This resulted in energy savings associated with ventilation and the elimination of mechanical cooling and air conditioning of corridors and stairwells.

Solar array and green roof atop the Net Zero building. Credit: City of Vancouver, 2009

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We combined a green roof with the solar array – so the rooftop does more than one thing.
Stu Lyon, Principal, gBL Architects

Close-up of solar tubes. Credit: Danny Singer, 2009

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SYSTEMS DESIGN

A Low-Tech Solution

A myth about carbon neutral buildings is that they must incorporate futuristic, state-of-the-art technology. “Some Net Zero buildings rely heavily on technology – it takes a person with a PhD to operate them,” says Albert Bicol of Cobalt Engineering. “But in our case we really tried to max out the KISS principle: keep it simple, stupid. We didn’t rely on high-tech equipment, just high quality materials and smart design.”

The building relies first and foremost on passive design. The building features an enhanced envelope, including triple-pane windows. The walls are insulated on the outside, a practice that can be costly, but pays off in energy efficiency (see Chapter 4, Exterior Insulated Wall Assemblies). In the interior, thermal mass is used to regulate the temperature. The envelope has an effective exterior wall R-value of R20, roof R-value of R30 and glazing effective U-value of 0.25.

The team reduced thermal bridging, wherein building components (such as floor slabs) conduct energy (heat) from the inside to the outside. This was accomplished by applying insulation on the upper surface of the slab extensions (under the walking surface) and partially insulating the underside of these balcony and walkway structures. The building’s other innovative design features include vertical ventilation shafts. The shafts are kept at a negative pressure, so air is expelled by passive means out of the suites and upward to the roof.

“This isn’t really a high-tech building or a technological marvel,” says Ramslie. “What it does have is really good insulation, well-placed glazing and a number of other key passive design features. What we really learned is that buildings of the future are really buildings of the past.”

Ostojic agrees. “In many senses, the more we rely on technology, the worse off we are,” he says. “Take this building. Years from now, the (solar) technology applied on this building will be obsolete – but the smart design will remain.”

The floor plan in the Net Zero building was designed to maximize cross ventilation and daylighting.

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GETTING TO ZERO: A COMPREHENSIVE APPROACH

Occupant Engagement

Another key element of the Net Zero strategy was to reduce energy consumption by engaging occupants to use less energy, since a building’s energy consumption in kilowatt-hours is determined in part by the design of the building, and in part by the occupant (see diagram). “We covered everything on this project, from design to influencing occupants’ behaviour. How we took care of the ‘hours’ part of the equation is a great part of the story,” says Bicol, referring to the element of the energy consumption equation that is determined by the occupant’s consumption pattern.

In the SEFC Net Zero building, occupants will be informed of the goals of the building, and encouraged to change their behaviour to reduce their consumption and help the project maintain its Net Zero balance. A large part of this strategy will be achieved through the installation of energy meters in every suite (see ‘Resource Management’ in Chapter 5). By looking at the meters, occupants have real-time feedback about how much energy they are using.

“We considered how the occupants and operations and maintenance people would use the building. This is not common practice. What you see most often is that people will design a building and then just leave it. In the case of this project, we put systems in place to make sure it operated properly. There should be an educational component for the people that live in such a high performing building,” says Bicol. In the SEFC Net Zero building, the City of Vancouver will provide a users’ manual for occupants and operations people, detailing how user activity affects energy consumption.

Adaptability and Aging in Place

Net Zero Energy Balance

Measuring Energy Performance
kWh/m2/year

The most accurate way of determining a building’s level of energy consumption is kWh/m2/year – that is, annual energy use per area. The kWh/m2/yr measurement is a common unit used to assess and compare the energy performance of buildings.

kW = kilowatt, the amount of energy consumed. This is determined by the design team. Efficient design will lower total kilowatts consumed.

h = hours. This is determined by the user. The hours number is determined by the energy use pattern of the occupant. For example, if the occupant leaves the TV on 24 hours a day, the number will go up.

m2 = the area, which provides an indication of the energy intensity of the building design. The lower the usage of energy per area, the more energy efficient the building. The importance of this standardized metric for energy efficiency is the ability to compare different buildings and different designs to each other, and determine which provides the best efficiency per unit of space.

A BALANCING ACT

First, Reduce Demand

The approach to achieving the Net Zero goal includes three overarching elements: energy efficient design, occupant engagement and energy generation. Using data from BC Housing and BC Hydro, the design team determined the annual energy consumption of a conventional building in order to establish a baseline annual consumption. The estimate reflected average energy use in similar type buildings – affordable seniors’ housing
of a similar size and proportion.

Energy loads were broken down into uses, so that the team would be able to address each end-use individually, as well as the building’s overall performance. For example, energy loads for appliances such as washer-dryers were managed by specifying low energy models. On the whole building level, performance was addressed by looking at the building’s systems, such as the design of its envelope and mechanical systems.

Second, Generate Energy Onsite

To balance the Net Zero equation, the team looked for opportunities to source energy onsite. “The best move is to first look for opportunities to recycle energy,” says Bicol. “You need to think outside of the box: look for synergies, turn waste into a resource.”

The ground floor of Parcel 9, the site of Net Zero building, is occupied by a large grocery store. This became a valuable energy resource for the Net Zero building. “One of the greatest opportunities we took advantage of was using the discarded heat from the grocery store,” says Stu Lyon of gBL Architects. Using a heat recovery system, the project team re-purposed waste heat from the grocery store’s refrigeration system, using it to preheat the residential hot potable water.

The team then explored renewable energy opportunities. A solar photovoltaic (PV) system was considered, but proved to be unfeasible. “One lesson we learned is that in a small urban site, we are limited in the amount of area on site that we have for typical renewable energy systems – it’s difficult to achieve enough area of those products on your own site to meet your energy needs,” says Lyon. “We talked about cladding the building in PV, things like that. Unfortunately, although we had a south-facing building, the building has limited access to sun, with over-shadowing from other buildings. And forget wind turbines – you’d need a field of those.”

After much investigation, the team concluded that solar thermal was the most appropriate technology for this project. Solar thermal systems use the sun’s energy to heat water. A 480-square-foot solar thermal system, made up of 72 panels, each with 16 vacuum tubes, was installed in two parts – on the roof of the building and on the roof of an adjacent affordable housing building on Parcel 5. Combined with the reduction strategy and heat recovery technology, the solar thermal system provides the balance of the annual energy equation.

Looking up at the solar array atop Net Zero building. Credit: City of Vancouver, 2009 (left)/Danny Singer, 2009 (right)

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INTEGRATED ENERGY STRATEGY

A. DESIGN & OCCUPANT ENGAGEMENT Energy consumption is reduced through efficient building design and occupant engagement. B. HEAT RECOVERY Heat recovered from the grocery store’s refrigeration system provides space heating for the building C. SOLAR HOT WATER ARRAY Arrays on two buildings provide the remainder of energy to meet the net zero balance. The solar installations provide hot water to the building and excess heat is sold to the Neighbourhood Energy Utility (NEU) (D) and used in adjacent buildings. Energy Savings Before the addition of renewable energy, the Net Zero building’s annual energy savings compared to a conventional building is 68%. With the energy production from the solar hot water system as well as the heat recovery from the grocery store refrigeration system, the building achieves Net Zero energy. Including the renewable energy contribution, the predicted annual GHG savings for the building compared to a baseline model is equal to roughly 280 tonnes of carbon dioxide equivalent.

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Thermal Net-Metering

On long, sunny summer days, the solar thermal arrays will produce an abundance of heat energy – an amount that far exceeds the building’s demand. During the winter, when the sun is often obscured by clouds and the days are shorter, the rooftop solar arrays will be less efficient. To address these seasonal fluctuations in solar heat production, the City of Vancouver and the Neighbourhood Energy Utility (NEU) devised a “thermal net metering” system. Through this agreement, excess hot water produced by the solar thermal system that is not used by the building is transferred to the NEU and distributed for use in other buildings on the SEFC site. Conversely, on low-production winter days, the Net Zero building will derive the balance of its heat energy from the NEU.

“The building is successful because of its context,” says Ramslie. “It would not achieve its energy goals if it were not connected to the Neighbourhood Energy Utility network and therefore able to export heat energy.” Similarly, the building was only able to meet its energy production goals because it was able to use the rooftop of a neighbouring building for solar panels, and draw waste energy from the adjoining supermarket.

The interrelationships between the buildings provide a useful lesson, a model that is transferable to future projects across Canada and beyond. According to the 2006 census, four out of five Canadians (more than 25 million people) live in urban areas. As the urban population continues to rise, it is crucial for Canadians to explore ways of applying and integrating clean energy technologies in an urban context. Implementing renewable technologies in a dense urban environment presents challenges that include shading from neighbouring buildings, limited site area and managing stakeholder relationships.

The approach taken at SEFC turned the challenge of a restrictive urban environment into an opportunity to establish relationships between the buildings and the various energy systems. “This process ended up delivering a high-performing building relying mostly on passive design, and proving that such projects are business models of urban collaboration towards collective targets, rather than isolated design exercises,” says Undurraga.

LESSONS LEARNED

Performance Indicators

Although the design team went to great lengths to estimate the building’s annual energy balance, it’s not enough to design a Net Zero building and assume that it will meet its projected performance objectives. Once the building is occupied, it is key to monitor the building’s systems and track its actual performance. The building has a monitoring system in place that will record its performance over time to measure the success of the chosen technologies, and offer lessons for future applications. “Monitoring is fundamental. If we don’t have feedback and reporting, we don’t have Net Zero,” says Ostojic.

Education and Engagement

Behaviour change – the human factor – is an element that is often overlooked in discussion of sustainable design. When trying to meet the Net Zero goal, the design team had to consider how the occupants would use the building. Part of the occupant agreement for the building is that the occupants must be made aware of the building’s objectives and their role in helping to meet them. “You know you’ve achieved a successful green building not when you get the plaque, but when occupants are engaged,” says Ramslie.

Collaboration

The strategy to meet the Net Zero objective emerged from a dedicated integrated design team, with each member bringing individual expertise and a commitment to out-of-the box thinking. With a shared vision, the diverse team of professionals met regularly to assess their progress. “I learned that good buildings are a collective effort of design that involves clients, city officials, users, a cohesive design team, and a well-crafted set of objectives and road map. Learning from the best in doing so changed forever my understanding of architecture,” says Undurraga.

Transferability

“This project was a great opportunity: it was Vancouver’s first trial at a Net Zero multi-unit residential building. As we designed the building, we thought about how transferable this would be to other sites in Vancouver, how it could inform future development. This building, the shape and footprint is similar to a typical Vancouver 120-foot deep site. Theoretically, the lessons that we learned here can be applied to sites around the city,” says Lyon.

CHALLENGE

“For local governments to make it easier to transfer energy across property lines, in order to boost efficiency, share resources and create opportunities for turning waste into fuel.

“ Monitoring is fundamental. If we don’t have feedback and reporting,
we don’t have Net Zero.” Goran Ostojic, Principal, Cobalt Engineering.


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