The Challenge of the Aging Building
Retrofit or Rebuild?
Sustainable, or ‘green’, buildings are becoming the norm when we talk about new construction projects. With a range of certifications available, it’s hard to find a new development that doesn’t boast a LEED, BuiltGreen, PassiveHaus, or EnergyStar rating. This is particularly apparent in cities like Vancouver where building bylaws require energy reductions of 20% below 2007 levels by 2020, and to be “carbon neutral” by 2030, for some project types.
Pursuing a high standard of building performance is a step in the right direction to battle climate change, but what about those buildings that already exist? It is easy to look at a run-down, 1960’s condo and assume it should be torn down and replaced with a shiny new build. However, new research has thoroughly examined climate change impacts associated with new builds and compared these against retrofit projects.
The results are in: retrofit is the way to go.
The Greenest Building
Preservation Green Lab presents a compelling study, published in 2011, titled The Greenest Building, which concluded that “building reuse almost always offers environmental savings over demolition and new construction”. The study looked at the relative effects a retrofit project would have compared with a new build over several building types including single- and multi-family residential, commercial office, urban village mixed use and elementary school. Evaluating the impacts of climate change, human health, ecosystem quality, and resource depletion, each typology, except for converting a warehouse to multi-family residence, showed increased environmental performance between 5 and 46%.
Life Cycle Analysis
An important factor in the study was the use of Life Cycle Analysis (LCA). This methodology considers the energy use and environmental impacts resulting from a material’s entire journey from cradle to grave. In comparison, most energy analyses only measure the operational impacts over a set amount of time, often one year (step 5 in the diagram below).
Using the LCA approach is particularly important when considering the full impacts of replacement projects, as the environmental costs of tearing down the old building are accounted for.
This study finds that it takes 10 to 80 years for a new building that is 30% more efficient than an average-performing existing building to overcome, through efficient operations, the negative climate change impacts related to the construction process. (Preservation Green Lab, 2011)
The Role of Operations and Maintenance
Proper operations and maintenance is vital to the performance of a building, and is, in fact, the key element in achieving high-performance.
Energy use in buildings can be reduced by 10-40% by improving operational strategies (Claridge, 1996)
Designing a building to the highest environmental standard and using all the newest technology out there does not mean the building will perform well. Achieving high-performance can only be obtained with the skills and knowledge of trained operators. These dedicated Energy Managers are responsible for monitoring building performance on a real-time level to quickly adjust controls and settings to optimize the performance of individual building systems.
Retrofitting an existing building to a high-performance building is almost always the better choice compared with demolishing and building new. The decrease in environmental impacts are immediate, and, over the lifespan of a building, are generally greater than those offered by new construction. Keys to a successful retrofit are choosing appropriate materials and ensuring a trained Energy Manager will oversee the ongoing operations and maintenance.
Energy efficiency in existing buildings is our greatest opportunity for a sustainable future (ASHRAE, 2015)
City of Vancouver, Energy Requirements, Forms, and Checklists for Large and Retail/ Commercial Buildings. http://vancouver.ca/home-property-development/large-building-energy-requirements-forms-checklists.aspx
Preservation Green Lab, The Greenest Building: Quantifying the Environmental Value of Building Reuse, 2011. https://www.archdaily.com/204449/the-greenest-building-quantifying-the-environmental-value-of-building-reuse
ASHRAE, Energy Star Guidelines for Energy Management. https://www.energystar.gov/buildings/about-us/how-can-we-help-you/build-energy-program/guidelines