These days, living in a major metropolitan centre carries the strong likelihood of living in the shadows of skyscrapers. Tall building development has been an increasing trend within urban environments worldwide, sparked by rapid population growth and increased urbanization, technological advancements, the need for affordable housing, and inter-urban competition between cities. These factors, coupled with the establishment of density targets by governing bodies, have made tall buildings a highly effective method for accommodating growth while maximizing revenue.
However, in recent years, there has been increasing concern around how these developments impact the fabric of the cities they serve. With the proliferation of high-rise development has also come the consequences: densely packed skyscrapers inherently create physical, environmental and experiential impacts. If poorly designed, these structures may cause wind tunnels, shadow impacts and/or privacy concerns for neighbouring properties.
At the root of these complications lies the question of compatibility and appropriateness of these buildings within the surrounding community. Various planning approaches have emerged in attempts to address these issues, the most prominent at this time being tall building design guidelines.
Design guidelines
Guidelines may be initiated as a tool to advance the vision, objectives and policies of an official plan, but they are not subject to the same statutory process as an official plan or zoning by-law. This lack of legal authority has called into question the effectiveness of guidelines in shaping the design of tall buildings; is this area of planning a context-specific issue that needs to be addressed case-by-case? Or should municipalities enforce restrictions on tall building design to ensure the issues with their development are prevented?
To further understand this debate, we conducted an analysis on tall building development in the City of Toronto, powered by WSP’s PRIME for Cities platform, to determine if development has been adhering to the current guidelines. More specifically, this analysis measured the applicability of two standards within the guidelines: floor plate area and separation distance.
These standards were chosen as they are two of the main components of tower design, and are related to many of the potential impacts of tall buildings; for instance, oversized floor plates and inadequate separation distances between buildings may impact access to sunlight both within the building and at the pedestrian level with shadowing, create privacy concerns for residents within and surrounding the building, and create potential wind tunnel effects due to form or lack of architectural mitigation details.
The Toronto Tall Buildings Guideline 3.2.1 requires that floor plates be limited to 750 m2 or less per floor (Figure 2), while Guideline 3.2.3 requires a separation distance of 12.5 m or more from the side/rear property line or centre line of an abutting lane, and 25 m between towers on the same site (Figure 2).
Methodology
Council-approved development applications throughout the city were analyzed against the floor plate area and tower separation guidelines to determine if developers were implementing these parameters, or if Council and city staff were approving applications regardless of adherence or non-adherence. PRIME for Cities, in conjunction with City of Toronto staff reports and Ontario Municipal Board (now Local Planning Appeals Tribunal) decisions, were used to identify these parameters. The results were analyzed based on strict compliance to the guidelines, as well as using a bell curve analysis to determine the extent to which they deviated.
Only the development applications which were 20 or more storeys tall and submitted between May 2013 and September 2016 were included in this analysis, to narrow the scope to only those applications with the greatest impact. This resulted in a total of 83 applications that fell within the parameters of this review.
Results
From the 83 sampled cases, only 10 complied with both the floor plate and tower separation standards (Figure 3); when focusing specifically on the downtown core, only one application complied with both standards (Figure 4).
Figure 3: Location of sampled cases in compliance and non-compliance. Source WSP, 2016
Figure 4: Location of sampled cases in compliance and non-compliance within the downtown core. Source WSP, 2016
When considered from a proportional standpoint, only 17 per cent of the sampled cases complied with both standards (Figure 5); this percentage rose when analyzing each standard separately, ranging between approximately 41 per cent to 57 per cent compliance (Figures 6 – 7). It is interesting to note that the separation distance standard was less often complied with than the floor plate standard. This variation is likely because the former standard requires contextual application with adjacent buildings whereas the latter standard is solely based on tower design.
Figures 5 – 7: Percentage of applications in compliance and non-compliance with the Guideline standards, for each standard separately and both together. Source WSP, 2016
As the guidelines are only intended to provide direction on best practices and performance standards for tall building design, it is fair to say that applications which fall within one standard deviation from the standard are generally following the intent of the guidelines, if the deviation is justified. For this reason, the distribution of cases was analyzed using a bell curve falling around the standard (Figures 8 – 9); although all curves were skewed, at least two-thirds of all cases fell within one standard deviation of the set mean.
Figure 8: Distribution of sampled cases around the 750m2 floor plate standard. Source WSP, 2016
Figure 9: Distribution of sampled cases around the 25m tower separation standard. Source WSP, 2016
17 cases fell beyond one standard deviation, with more exceeding this limit for the tower separation guideline than the floor plate guideline. 13 of these cases had a residential tower use, with the exception of two which had office uses and two which were proposed for different types of accommodation space (i.e. student residence, hotel).
Conclusions
The results show that although the majority of the approved applications fall within an acceptable range, they still deviate from strict compliance to the recommended standards. However, most applications fall within one standard deviation of the mean, indicating that these standards are in fact guiding developments. Reasons for deviation are often justified within planning rationale reports and/or staff reports, allowing for contextual understanding on a site by site basis. For example, one development was approved despite not meeting the minimum separation distance because the adjacent building did not have windows on the abutting side. The lack of windows eliminated privacy concerns, deeming deviation appropriate in this case.
Although land use planning is mainly managed through policy and regulatory parameters, there are some aspects of development that vary based on the built environment and surrounding context. In these instances, regulatory parameters cannot accurately dictate the varying needs of the context at hand. As such, this analysis confirms and supports guidelines as an effective form of control for built form and planning matters that are context-dependent, such as tall building design.
The specific design needs of these developments should be identified and resolved by the development team and municipal staff, who can work together to determine development impacts on a site-specific basis and reach a solution that looks beyond numerical requirements to holistically understand the context. In these highly individualized, or site-specific cases, using a specialized tool like PRIME for Cities makes all the difference. At WSP, our PRIME team will continue to parse the complex, dynamic and versatile needs of these context-specific aspects of development to inform and advise on solutions for our clients.
For more information about how PRIME for Cities can help with your next project, please contact us at [email protected].
