Sundance

Project Description

Planning the Retrofit

Overview

In 2017, the Sundance Housing Co-op in Edmonton identified a unique opportunity to align upcoming capital projects: renewing its mortgage, re-signing its land lease with the City of Edmonton, and undertaking necessary exterior maintenance on its 59 original townhouse units. Instead of tackling these independently, the community chose a deep retrofit to address long-term comfort, maintenance, and climate goals in one comprehensive project. Ultimately, this reduced their energy needs by 70-80%, and eliminated the need for gas lines in the original 59 units.

1. Planning the Retrofit

Objectives

• Upgrade building envelopes

• Replace all windows with high-efficiency units

• Electrify mechanical systems and eliminate gas service

• Install solar PV arrays

• Improve future flexibility by enlarging basement windows and adding daylighting options

Financing and Partnerships

• Servus Credit Union: Refinanced the mortgage (previously held with CMHC) at a better rate, bundling the retrofit costs into the new mortgage.

• City of Edmonton: Extended the land lease by 60 years, contingent on completion of the retrofit.

• Natural Resources Canada (NRCan): Provided $2.5 million in funding, with the expectation that Sundance would pilot the Energiesprong deep retrofit approach.

Retrofit Approach

• Energiesprong: A Dutch method using prefabricated panels to provide insulation, air sealing, and new exterior finishes in a streamlined process.

• Adaptations for Canadian context:

  • Sundance’s complex geometry (cantilevers, wall jogs, and tight corners) required custom solutions.

  • Some windows and doors were relocated to accommodate panels.

  • Site-built details were added where prefab panels were not feasible.

  • Cellulose insulation was used instead of spray foam to reduce embodied carbon.

  • Panels were installed with siding left off in some areas to allow insulation to be blown in. The weather resistant barriers were installed with an allowance for sealing to adjacent panels. The WRB also served as the air barrier in this project.

  • Scissor trusses were added above the existing roofs to accommodate additional insulation and wider overhangs.

  • Comprehensive air barrier work was done to minimize air infiltration.

Pilot and Scale-up

Two buildings were retrofitted first to refine processes before full implementation on the remaining units.

Renewable Energy Generation

Sundance installed an extensive rooftop solar system, with multiple arrays split into 4 different sections. Each of the four sections has an individual microgeneration agreement, and an electrical shed to house the necessary electrical equipment. Each shed contains two 33.3 kW inverters, which bring each section and microgeneration agreement to 66.6 kW. Eight electrical inverters were installed on site, each rated at 33 kW AC. Two of these inverters have a sticker reading 50 kW but the manufacturer dialed back the inverters to meet code requirements. This is a common practice when the required sizes of inverters are unavailable.

To reach full net-zero, more on-site solar PV is required. In the interim, the co-op has entered into a Power Purchase Agreement (PPA) with Foothills Energy Co-op to cover remaining energy needs with renewable electricity.

Read more about the Sundance Housing retrofit.

Drawings or Details

Photos

Pre Retrofit

During Construction

Post Retrofit