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From the Design Quarterly: Retrofitting today’s buildings for a sustainable future

July 25, 2019

By Graham Twyford-Miles

Most existing buildings will still be in use 50 years from now. Retrofitting for sustainability is critical to a low-carbon future.

The current built environment consumes energy and releases greenhouse gases. If we’re serious about the transition to a low-carbon future or meeting commitments under the Paris Agreement, we need to talk about the carbon savings potential of existing buildings.

Even if every new building were designed for net zero energy, we’d still be faced with the significant carbon footprint of North America’s existing building stock. The majority of our existing buildings will still be in use 50 years from now, so retrofitting them is key to decarbonizing the built environment.

Building retrofits present design teams with complex challenges. But retrofits can result in a renewed asset that produces less carbon, uses less energy, improves occupant health and well-being, and costs less to own and operate.

We need to change how we think about existing building projects. Evolving government priorities and regulations will encourage and eventually require retrofits for carbon savings and energy efficiency, and the private sector will follow suit. But that still begs the question, just how do we make yesterday’s buildings less carbon-intensive and what are realistic targets for retrofitting? How much can we do on a generous budget? What about a slim budget?

Canada, as a signatory to the Paris Agreement, is targeting reductions in greenhouse gas (GHG) emissions for 2030, and buildings are a significant part of that reduction. Retrofitting government buildings is an important step in demonstrating leadership in emissions reductions.

It’s in this context of targeted reductions that real estate management company Brookfield Global Integrated Solutions (BGIS) has undertaken building retrofit studies for key buildings in its Canadian portfolio. BGIS has engaged our team to provide detailed energy assessments, building performance modeling, financial analysis, and performance engineering services to support major upgrades to the facilities it operates.

Feasibility studies are an important first step in assessing the possibilities for retrofitting, and the range of strategies available for achieving carbon reduction. In detailed feasibility studies on more than 30 BGIS-managed buildings across Canada, we are investigating design concepts that will bring each building closer to net zero carbon operations. These studies include 25-year life cycle cost analysis of the buildings and recommendations for improving performance, which are essential for finding a pathway to carbon neutrality. By bringing a whole-building design approach to these studies, we maximize the potential for carbon savings and energy reduction over the life of the building.

Here is the 7-step process we’re implementing:

1. Existing building condition assessment: Complete a detailed study of energy use by the existing building and its systems.

2. Energy model development: Develop a detailed digital model calibrated to available utility data following ASHRAE Guideline 14 and aligned with actual and potential building operations.

3. Baseline generation: Capture current and potential baselines.

4. Energy efficiency measure (EEM) selection: Work the project team to identify EEMs suitable for the building based on performance, cost and replacement schedule.

5. Energy conservation measure analysis: Perform detailed energy simulations to assess the impact of each EEM.

6. Financial analysis: Complete a lifecycle cost analysis to evaluate the cost of each EEM, testing against operations, maintenance, and replacement as well as energy costs.

7. Recommendations and reporting: Complete detailed report showing the results of the above analysis and the recommendations agreed to through multiple client workshops and review cycles.

To find best option for carbon reduction within budget, we leverage digital tools from parametric design to solar modeling software. By doing so, we can modulate options for design, systems, performance, and cost. Studies like this are vast, complex, and time-consuming undertakings that require multi-disciplinary collaboration and expertise in everything from building envelope to efficient mechanical systems to the cutting edge of parametric modeling software. But they are critical in achieving our carbon targets. It will take many studies such as this to kick-start what could be one of the most significant undertakings on the road toward a net zero carbon future.

Read and download the Design Quarterly Issue 06 | Destination Zero

Performance targets

We conduct an in-depth investigation of design strategies and EEMs that can substantially improve the energy performance and reduce the energy cost and GHG emissions of the subject building. We bundle the various possibilities for design interventions in four buckets; each defined by a different goal—ranging from the sky’s the limit budget option to a bare-bones “what would it take to reduce carbon by 20%” option.

1. Minimal departmental standard: Reduces the building’s energy consumption by 24% from requirements of the National Energy Code of Canada for Buildings (NECB) 2011.

2. Highest GHG reductions while achieving a positive net-present value (NPV) within 25 years: Reduces building’s carbon footprint (annual GHG emissions) as much as possible, while producing a positive NPV for the project when evaluated over a 25-year lifecycle.

3. Carbon neutral: Achieves carbon neutrality. The bundle of EEMs reduces the carbon footprint of the building to net zero without resorting to carbon offsets or renewable energy purchase.

4. Best value: Provides the best compromise for the building in terms of achieving significant GHG reductions and overall project feasibility.

  • Graham Twyford-Miles

    Graham's passionate about improving the sustainability of our communities through thoughtful development planning and creative, performance-based design.

    Contact Graham
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