Given the energy crisis, access to the sun’s energy for our buildings is essential for enabling passive and active solar measures: for daylighting, hot water, electricity, and for heating and cooling spaces (building heating loads can be decreased by up to 50%[ii] according to the DOE EERE and up to 75% with aggressive measures according to the Whole Building Design Guide[iii]). Further, since data show daylight access is a vital factor to occupants’ health and productivity, we know that solar access also impacts their employers’ bottom lines.
Yet, as the US Department of Energy’s Energy Efficiency and Renewables notes, codes and zoning ordinances have made solar access problematic. In fact a multitude of regulatory barriers to solar access - including height, setbacks and orientation - exist in the U.S. and Canada.
For instance, despite the city of Toronto’s 2007 Green Development Standard – guidelines which support both passive solar heating and natural lighting, project proponents of Toronto townhouses with passive solar design in Canada Mortgage & Housing’s Equilibrium program have had to go through various regulatory ‘hoops’ to move forward. Given design measures included passive solar heating and daylighting, the buildings’ orientation meant entrances were optimally not on-street, which was contra to the 2003 Toronto Urban Design Infill Townhouse guidelines.
Contrasting examples - where intent matched regulatory practice - include: Madison, Wisconsin’s land subdivision regulations which mandate street and subdivision lot orientations as well as the siting of trees to optimize solar access, and the Municipal code/Charter and Land use codes for the city of Fort Collins in Colorado that protects against shading windows or gardens for more than 3 months annually – although this does not include high-density districts like downtown.
Solar access and benefits of trees
There is a dynamic tension between ensuring solar access for passive and active measures, and the benefits of preserving deciduous trees for buildings’ summer solar shading to reduce cooling loads and urban heat island effects as well as for carbon sinks. Trees also contribute to occupant benefits via ‘natural views’, which impact property values. Researchers have noted[iv] [v]that treed residential properties in Canada and the U.S. can have higher resale values which vary from 5-25%. As well, treed properties have been found to sell faster than similar non-treed counterparts. [vi]
It is also becoming increasingly important to extend the discussion on solar access to include protection of individual property and community urban agriculture access to sunlight, due to:
· heightened recognition of food mile issues
· rising food prices e.g. due to agricultural land competition from fuel crops, and
· consequent concerns about food security
An example: as a summer cooling measure I nurtured a proliferation of (ornamental) vines on my balcony – until a few years ago when a neighbouring development cut my 6 hours of daily eastern-exposure sunlight down to 4. This now also limits the veggies I can grow.
Human needs for shade
Additionally, provision for maintaining urban shaded areas is vital in extreme heat conditions for people – especially vulnerable segments like older, very young or differently abled persons.
Urban scene is complex
Ensuring urban solar access for existing buildings seems problematic.
Commercial and residential high-rise properties have limited recourse where there are existing neighbouring structures shading solar access.
With some exceptions (where existing trees must be pruned to accommodate new active solar instalments),[vii] for older urban neighbourhoods with established tree canopies, optimal solar access solutions for both low-rise residential and commercial buildings subject to treed shade include options like tubular systems to introduce daylighting from non-shaded areas. As well, cooperative active solar installations could work (given regulatory support) on school or other local public properties. Such co-ops are likely to engender maintenance savings from economies of scale.
For those whom solar-accessible private productive gardening is limited, community gardens or allotments have become locales for community engagement, youth education, urban renewal, crime prevention, and cross-generational and –cultural exchange.[viii]
Imperfect solutions maybe, but with significant compensatory benefits.
Green Syndicated Columnist Sonja Persram is lead author of Marketing Green Buildings to Owners/Tenants of Leased Properties for the Canada Green Building Council (2007) with co-authors Nils Larsson (MRAIC) and Mark Lucuik (P.Eng, LEED AP). Ms. Persram wrote: Green Buildings: A Strategic Analysis of North American Markets for Frost & Sullivan (published 2006) addressing Energy, Water and Facilities Management; and the U.S.A. portion of International Sustainable Building Policy Initiatives, a 2007 study for Canada Mortgage & Housing Corporation whose project lead was Nils Larsson. She is a member of the CaGBC Greater Toronto Chapter’s Business Development Committee, USGBC’s Social Equity Task Force and the WorldGBC’s Tools & Projects Committee. Contact: Sustainable Alternatives Consulting Inc: email@example.com
[vi] Friends of the Don East, op.cit