Shadow analysis for 2538 Birch Street rezoning

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How long are the shadows that would be cast by the proposed 28-storey tower at 2538 Birch Street? (The current Public Hearing with final decision expected on July 21, 2020, is to allow 12 more storeys above the already-approved rezoning to 16 storeys.)

This slideshow shows the length of shadows cast for a number of different days during the year, including the shoulder season and the winter solstice. The City of Vancouver in the past has looked at 4 pm times for other rezoning applications, but it did not review this timeframe for this particular rezoning. Rather, the shadow studies presented to Mayor, Council and the public only showed 10:00 am to 2:00 pm on the solstices and the equinoxes (10 am, 11 am, 12 pm, 1 pm and 2 pm). The applicant and City staff selection of dates and times understate the shadow impacts.

Shadows, solar access and sky access are important considerations in urban planning. Sunlight is positive for human mental and physical health. Shadows affect heating and cooling demand in affected buildings in the neighbourhood. Light and shadows also have impact on future opportunities to use solar thermal and photovoltaic power for heating and electricity generation, etc.

About the model

The aerial photographs are from the City’s OpenData portal (orthophotos). The geometry for the base model was provided by the City of Vancouver via a FOI request for the buildings and terrain.

The software used for generating the shadows is Unreal Engine 4.25.1 from Epic Games. There is built in functionality to show realtime shadows based on the location of the sun for anytime time of the year for any location on the planet. This game engine is used in video games such as Fortnite and Gears 5. Unreal Engine is entirely free for non-game uses such as architecture. Could such models be used by City Councillors and members of the public to interactively see shadow impacts of a proposed rezoning?

Note that there’s one hour ‘change’ in time while jumping to and from Daylight Savings Time impacts comparative analysis between times of the year that are in Standard Time.

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