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From aging to efficient: Three steps to transforming obsolete buildings

Buildings designed to energy codes of the past can still attain Net Zero status

By: Andrew Penner, Ottawa, ON

Energy savings of 30 to 50% are achievable in our aging building stock. We know that this is possible based on the measurable performance of leading edge design strategies. However, some in the design industry seem hesitant to change the way we have always designed, constructed and operated buildings. It’s time for a change.

The situation
Before global warming and climate change, and before the cost of energy struck fear into the hearts of building managers, we designed buildings with little regard for thermal performance and energy efficiency. Building and energy codes have evolved and energy costs have skyrocketed since these buildings were initially designed and constructed. Today, building owners must juggle financial and operational priorities while they contemplate mid-life full building renovations to decrease their mounting energy costs.

Commercial, institutional, and public buildings represent approximately 17% of all energy consumed in Canada. Residential buildings represent an additional 17%, for a total of 1/3 of all energy consumed.

Within the commercial and institutional sectors, there are more than 80,000 buildings, more than 50% of which are over 35 years old. Almost 70% are more than 25 years old.

Better energy efficiency is possible
The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has published guidelines for improving building designs to reduce building energy consumption by 30-50%. From this we might infer that as much as 30% of energy consumed by our existing building stock is wasted – or at the very least, avoidable.

What we need is a dramatic shift in our approach. We need to start looking at the building as a structure that coexists with the weather; that is weather responsive, staying warm in the winter and cool in the summer with minimum use of energy. This implies a building that has a good building envelope that coexists and works with the rest of the HVAC equipment. This requires that we move away from conventional designs, and move toward more passive design strategies that move less air and that need less air conditioning and heating.

The reality is that building owners often prefer to put their budgets toward superficial improvements—like finishes and renovations—rather than improve their building’s efficiency. How do you make informed decisions on building renewal and improvement measures competing for the same, limited funding?

Our current Federal Administration is about to set the example. Having recently ratified the COP21 agreement, through the Federal Sustainable Development Strategy, they have committed to carbon neutrality in federally owned buildings by 2030. This goal is not going to be met by replacing building components alone. A deep dive and leap of faith will be required.

But is it possible?

How do you transform an obsolete building into a high performance, or Net Zero building?

Defining a path
In many cases, comparison between energy saving measures is challenging, because each energy saving measure impacts building operations and efficiency differently. Sometimes energy saving measures complement each other. Other times, they compete with one another.

One solution is to use a process known as the advanced parametric analysis model. This model enables us to generate an unlimited number of dependent and independent variables, which can be analyzed to construct an unlimited number of scenarios. This allows for a more comprehensive plan and provides a clear advantage over analysis of singular measures on a one at a time basis, parametric analysis allows a myriad of parameters and variables to be evaluated concurrently. With an eye on the prize (whatever the goal is – i.e. energy utilization index, Energy Star® score, etc.), the resulting data set can be used to identify only those scenarios which can produce the sought after energy reduction and performance requirements.

Then, applying financial life cycle costing analysis to those technically feasible scenarios, an owner can make a truly informed decision on how to address the mid-life refit of their building. How we determine the course of action that meets the goals and objectives of the owner can be distilled into a few steps.

Step 1: Defining options
First, it’s time for blue-sky thinking. What building systems could be improved upon and by how much?

Building performance optimization measures will typically fall within the following categories:

  • Thermal performance for roof and wall systems
  • Thermal performance for windows and doors
  • Heating, ventilation, and air conditioning strategy
  • Heating, ventilation, and air conditioning component capacity and efficiency
  • Lighting system performance
  • Building operating parameters, set-points, and schedules

Building load minimization typically begins with building envelope. In existing buildings this poses a significant challenge. It is often difficult and cost prohibitive to improve the thermal performance of the building envelope. Under certain circumstances, however, improved and/or augmented window performance and shading can be accomplished. Once the envelope has been optimized to the extent possible, attention turns to internal loads – the things we plug in and equipment that keeps the building running.

Step 2: Establishing criteria of evaluation
Each improvement category is likely to be subject to incremental improvement. For instance:

  • Envelope system components can be updated in steps (which vary by thickness of insulation or panes of glass).
  • Heating, ventilation, and air conditioning strategies vary from the traditional to the cutting-edge (each strategy representing different efficiency and equipment configuration).

Internal heating and cooling loads are decoupled from ventilation loads – meaning that the equipment used to condition fresh outdoor air is separated from the equipment used to manage building loads. This strategy can result in a reduced volume of conditioned air delivered to the spaces, resulting in significant fan energy reductions. Implementation of such a dramatic strategy requires a departure from the traditional conditioned air delivery and the adoption of either underfloor air distribution or displacement ventilation.

Step 3: Simulation and selection
We know that making a decision about which energy saving measures to choose can be daunting, especially because multiple implementation scenarios exist. Through the development of a detailed simulation model, which accurately represents the building and integrates the building optimization measures and evaluation criteria, we can develop a diverse database, which includes every performance permutation.

The results from detailed simulation based parametric analysis, combined with life cycle costing analysis, can be used by building owners to compare scenarios in real time, and identify the scenarios which meet all their constraints and criteria for success.

The owner may still decide to proceed with largely cosmetic upgrades, but some will take the leap and transform their old buildings, achieving reduced operating expenses, increasing their property value, and even improving business productivity[1].

Conclusion
As an industry we have been gifted with a tremendous opportunity to engineer real change resulting in significant benefit to our clients’ bottom line, our environment, and our communities.

Andrew is an Associate for Stantec Ottawa, Ontario. With more than 14 years of experience, Andrew provides technical and team leadership to the Energy Management community, specializing in energy and water conservation assignments. Connect with Andrew.

Today, building owners must juggle financial and operational priorities while they contemplate mid-life full building renovations to decrease the energy costs of their aging building stock.

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