Energy Efficiency/Renewable Energy

Integrating envelope design, heat pumps, energy storage, renewables

By Chris Flood

Multi-Unit Residential Buildings (MURBs) occupy a critical place in Canada’s urban decarbonization strategy. These high-density residential forms are growing rapidly in every major city and represent a large share of new construction floor area. They also embody a paradox: MURBs can be more energy-efficient per capita than low-rise housing, yet their dependence on centralized heating and cooling systems, complex envelope geometries, and dense electrical loads present substantial challenges to achieving net-zero performance.

Against this backdrop, energy simulation is evolving from a compliance exercise into a design intelligence tool. For decades, simulations were deployed at the end of design – largely to demonstrate NECB or ASHRAE 90.1 compliance to regulators. Today, forward-looking design teams are integrating simulation from the earliest concept stages. This transition is enabling more robust decision-making around electrification, heat pump system selection, code compliance, and carbon reduction strategies.

This article explores the shift in the role of simulation, the pathways for electrification in MURBs, and how integrated modelling is helping teams navigate code complexity, manage grid impacts, and deliver projects that balance cost-effectiveness with sustainability.

From Compliance Tool to Design Intelligence

Historically, simulation models were “back-end” tools. A building was designed, and then a model was created to prove that it complied with minimum standards. The process was often siloed, with little feedback between the energy model and the architectural or mechanical design.

That paradigm is changing. Several factors are driving this evolution:

1. Code escalation: NECB 2020 introduces tighter envelope and system requirements. Provincial frameworks such as the BC Energy Step Code and the Toronto Green Standard demand not just compliance, but tiered performance improvements.

2. Electrification pressure: Cities and provinces are phasing out fossil-fuel-based heating, forcing design teams to compare heat pump strategies head-to-head.

3. Carbon accounting: Owners and regulators are increasingly prioritizing greenhouse gas intensity over raw energy use.

4. Grid constraints: Utilities face strain from coincident heating loads during cold snaps, making demand-side management and load shifting critical.

In this environment, simulation is being leveraged iteratively and strategically. Models are now decision-support engines, allowing engineers to test design concepts before they are fixed, explore alternative technologies, and quantify lifecycle cost and carbon outcomes.

Reducing Design Heating Loads:

The First Lever

A key insight from simulation-driven design is that load reduction often trumps system efficiency. A poorly insulated or leaky envelope forces even the best heat pump to work harder, inflating equipment sizes and utility bills.

Strategies to Reduce Heating Loads

1. Envelope Optimization:

High-performance glazing with low U-values and tuned solar heat gain coefficients (SHGCs).
Continuous insulation strategies to minimize thermal bridging.
Airtightness testing and detailing to reduce infiltration.

2. Internal Loads Management:

High-efficiency appliances and LED lighting.
Smart zoning and control strategies to avoid over-conditioning unoccupied spaces.

Chris Flood, a mechanical engineer with more than 20 years’ experience within the building services industry, is vice president, Canada, for IES.

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By Mark Hutchinson, Vice President, Green Building Programs, Canada Green Building Council

As the first municipality in Canada to adopt a Sustainable Building Policy (SBP), The City of Calgary is a leader in promoting green building. The City’s SBP has resulted in over 60 LEED-certified projects, including Canada’s first two LEED v4 Building Design and Construction (BD+C) certifications.

With a strong commitment to achieving building performance objectives, The City has leveraged LEED v4 to better focus on the integrative design process and optimizing energy performance to help meet its sustainability goals.

Sustainability in step with LEED

Officially approved by City Council in 2004, The City of Calgary’s SBP originally specified LEED certification for buildings owned or funded by The City. In 2019, Calgary City Council approved a policy update that required project teams to meet specific minimum sustainability performance requirements, many of which align with and are supported by LEED v4. These new requirements include: • A minimum 40 per cent energy and energy cost improvement over a National Energy Code for Buildings (NECB) 2011 baseline building; • Enhanced commissioning on energy and building envelope systems;

• Mandating the use of low-impact refrigerants (if used) that comply with LEED v4 requirements; • A minimum 35 per cent indoor water use reduction compared to the baseline consumption as defined by LEED;

• Achieving stormwater management requirements as defined by LEED v4; and • Minimum requirements to provide rough-in infrastructure for future solar photovoltaic (PV) and electric vehicle charging stations (if not already included in the design). While certification objectives are now established on a project-specific basis, LEED remains The City’s green building certification program of choice.

“In our opinion, LEED is still the most well-rounded green building certification program that most directly aligns with the City of Calgary’s Sustainable Building Policy,” says Tyler Young, a sustainable infrastructure engineer with The City.

Putting energy and atmosphere first

In 2018, Calgary City Council approved a Climate Resilience Strategy, aimed at preparing for and minimizing the impacts of a changing climate.

The strategy targets an 80 per cent reduction in citywide greenhouse gas (GHG) emissions below 2005 levels by 2050. To help achieve this goal, The City of Calgary requires minimum energy consumption and energy cost improvements above an NECB 2011 baseline building for their projects.

LEED’s Energy and Atmosphere credit category provides a framework to help The City achieve this goal. The City of Calgary utilized this credit category on its first three LEED v4 certified projects: The City of Calgary Organics Waste Diversion Facility – Administration & Education (A&E) Building, Stoney Transit Compressed Natural Gas (CNG) Bus Storage Facility, and City of Calgary Manchester Building M.

Taking the guesswork out of the design process

LEED v4’s integrative design process requirement is a key component in ensuring The City of Calgary’s sustainability objectives are reflected in each stage of a project’s design.

City projects benefit from having all team members at the table. Early on, they set the expectation for clear communication, especially around performance targets such as energy efficiency, water use or sustainable material usage. This approach allows consultant teams to better understand the project’s priorities and focus credits. It also helps generate more ideas and avoids unnecessary back-and-forth discussions.

“By clearly establishing the specific objectives we want to achieve early on and then using the LEED rating system as a tool to ensure we achieve these objectives, we’ve removed a lot of guesswork for our consulting teams as to how they should achieve our LEED certification targets,” says Young.

The municipality has since introduced a model that onboards the building performance optimization consulting team early in the process in many of their projects. This team consists of a green building consultant, energy modeller and commissioning authority and reports directly to The City, further improving communication.

Achieving more with LEED v4.1

As The City of Calgary works to improve the sustainability and performance of its building projects, the municipality has been able to leverage recent updates introduced in LEED v4.1 to validate its efforts. Young notes that for upcoming projects, The City is aiming for LEED v4 certification using LEED v4.1 new alternative compliance paths that make certain credit requirements more applicable and achievable, citing stormwater management as an example.

With the increased flexibility offered by LEED v4.1, The City of Calgary foresees it will continue to pursue LEED v4 and LEED v4.1 for most of the larger City-owned or City-funded projects. As The City of Calgary’s approach to sustainable building evolves, LEED certification remains an important tool in achieving The City’s performance objectives. “LEED continues to be the most holistic rating system, and because of this, continues to be the green building rating system of choice,” adds Young. To see more LEED case studies, visit cagbc.org/casestudies.