Make the most of the zoning process with CFD wind assessment

Orbital Stack confirms that a climate-responsive building design will meet a City’s wind guidelines through early stage CFD analysis.

Short on time? Here are the quick highlights:

  • A new eight-storey residence is proposed for an emerging neighbourhood, with close proximity to a lake and surrounded by low-rise buildings.
  • To ensure an intelligent, “wind-savvy” design will meet the City’s evolving wind criteria, the developer requested an early stage CFD analysis.
  • Fast, accurate results using Orbital Stack confirmed the design’s positive features will help moderate wind impacts and keep tenants and nearby pedestrians comfortable.
  • The flexibility of the Orbital Stack tool, allowed for design tweaks, without delaying the delivery of the results.

Artist’s rendering of the development courtesy of Richard Ziegler Architect.

The ask

An emerging east-end Toronto low-rise neighbourhood is poised for extensive development. With a renewed focus on microclimates in hot-market areas like this, the City requires developers to provide detailed wind assessments. This is especially important when wind flows are impacted by nearby Lake Ontario, as they are here.

With an intelligent and “wind-savvy” stepped-form design (ideal for reducing wind impacts) already in place, the developer approached RWDI for assistance to keep construction on track for a proposed eight-storey, 38-unit residential building along this community’s main artery.

Known as an innovative adapter of new technologies, the client wanted an early stage CFD (computational fluid dynamics) wind analysis that would provide fast, accurate results that satisfied the City’s requirements while revealing problem areas. Top of mind were the comfort and safety of pedestrians on and around the proposed development.

The challenges

Proximity to the lake and a low-rise surrounding neighbourhood create unique climate conditions in this very windy corner of the city. The client was faced with a daunting task: prove that the design’s thorough consideration of local climate and wind conditions would meet the City’s increasingly stringent requirements for pedestrian safety and comfort.

Unlike many other parts of Toronto, the proposed residential building is buffeted by strong winds coming from the north east and south west. These winds, running parallel to Kingston Road, create a channeling effect of wind along the street. In the summer, the dominant wind is from the east, with the site also experiencing frequent winds from the southwest and northwest. In the winter, winds from the west, southwest and northwest are frequent in addition to winds from easterly directions. Notably, strong winter winds exceeding 30 km/h, have the potential to create uncomfortable or severe wind conditions around any structure, depending on site exposure and development design.

To successfully provide a wind impact evaluation in support of the City’s Site Plan Control Application (SPA) requirements, the chose RWDI due to its reputation for providing a fast (and accurate) turnaround of wind analysis in order to keep the project moving forward without delays.

CFD results image
CFD simulation showing RWDI wind comfort criteria for the summer. The stepped design leads to acceptable conditions at street level, as well as identifying areas on some terraces where additional improvements could be made.

The solution

RWDI recommended using Orbital Stack, its leading-edge CFD tool, to evaluate wind comfort levels on pedestrian areas near and around the building. A number of factors made this the right choice, including the client’s informed view of innovative wind analysis methods and clear understanding of how climate and wind conditions impact design considerations.

Orbital Stack confirmed that potential wind impacts would be moderated by the stepped massing of the proposed design (see illustration below), along with its location adjacent to shorter buildings with lower roofs that help disrupt downwash.

With accurate wind data crucial for the project site, long-term meteorological statistics going back to 1989 were gathered from Billy Bishop Toronto City Airport, which is the closest data collection site in terms of both geography and climate. The wind statistics were then combined with simulated data and compared with pedestrian comfort criteria.

Knowing that time mattered to the client, Orbital Stack produced its microclimate analysis quickly. Speed, however, is just one aspect of the software’s capabilities, as was demonstrated on this project. With the detailed results provided by Orbital Stack, including insights for terraces and other public areas, RWDI was able to offer a wide scope for additional improvements.

Flexibility is also built into Orbital Stack, as was demonstrated when the client’s late-stage design change was incorporated into the wind analysis without delaying delivery of RWDI’s assessment.

“Smart solutions appeal to us, and Orbital Stack delivered on all fronts. The team was effective in illustrating the benefits of CFD and were willing to adapt to the changing needs of my project. I especially appreciated Orbital Stack’s ability to visually depict problem areas and offer context by showing the whole street and surrounding area.”

Finley McEwen, Beachco Management Ltd.

The result

While the proposed building is taller than most other structures in the neighbourhood—and therefore will redirect wind to ground level—the design’s positive features will help moderate wind impacts to a large extent. Orbital Stack determined that wind conditions at ground level, including main entrance and patio, should be appropriate for a building of this nature.

Other findings determined that the project is unlikely to have a notable influence on wind conditions for nearby properties, and that potentially uncomfortable winter wind speeds to the north and south of the site near the building corners won’t impact pedestrian areas. Wind control strategies were provided for a high-level terrace, making this space more user-friendly during warmer weather.

Ultimately, Orbital Stack allowed the client to see the whole wind climate picture around their proposal. They quickly confirmed that their design, that already included wind mitigation features, including set-back entrances and intelligently designed public spaces, was on the right track. Early testing ensures fewer issues later and more comfort for future tenants of the building.

Learn more about our vision and why RWDI turned Orbital Stack from a set of internal tools into a dedicated company.