Toronto Mayor's Tower Renewal Project: Explained by Canadian Apartment Magazine

Here's what Canadian Apartment Magazine's Brian Burton had to say about the Mayor's Tower Renewal Project.

The readers of Canadian Apartment Magazine are well aware that Canada’s existing apartment stock is an extremely valuable resource. The buildings have demonstrated their exceptional durability and were constructed with the benefit of the National Building Code which has served as a driving force in the continuous efforts to improve our building technology. The following article discusses efforts that are underway to revitalize these structures, improve their energy performance, extend their effective service life and enhance their value.

Background

Toronto has close to a thousand highrise apartment towers; more than any metropolis in North America (with the exception of New York City). It has been estimated that they consume a significant percentage of the GTA’s primary resources - electrical energy and water. (There are also a hundred thousand apartment buildings above eight stories within the Québec City to Windsor corridor.)

A considerable percentage of these buildings that were built in the 1960s and early 1970s are rapidly approaching the end of their effective service life and engineering studies suggest that 60 to 70 per cent require major repairs and component upgrades of some nature.

Toronto moves ahead with Tower Renewal Project

Toronto, after a great deal of study, has taken a number of steps to launch an ambitious revitalization project that will, if successful, involve the remediation of public and private buildings that meet an established criteria. The City Council recently passed a resolution outlining their plans to begin implementing a Tower Renewal Project (TRP) in 2011.

This initiative undoubtedly represents a tremendous long-term opportunity for all the stakeholders involved. The structures, in most cases are exceptionally sound from a structural point of view. Academics at the University of Toronto suggested in the Tower Renewal Guideline report that the concrete framework of these buildings was capable of performing adequately for a considerable length of time if protected from the elements by replaceable façade systems.

The same study validated the concept that comprehensive thermal overcladding retrofits of the entire building envelope, undertaken at the same time as downsizing or replacing any components or systems in the building that consume energy are an appropriate approach to achieving the goals of extending service life and enhancing value.

The study documented that many European countries have successfully used the technique and have proven the viability of the technique.

Creating the funding mechanism

As one might expect, these retrofits can be was quite expensive and the issue of funding and financing quickly emerged as one of the biggest challenges.

When the City of Toronto was researching the methods used to raise capital to repair buildings and infrastructure in the United States it was learned that 17 States in the US, including California, were successfully using an innovative new system to raise enough capital to undertake revitalizations - without using government funds.

It was proposed that Toronto, similar to these states in the US, would ask the provincial government to revise existing legislation, create a Tower Renewal Corporation, and then market bonds on pubic stock markets that would return a reasonable investment based on the revenue that is produced by making improvements in energy efficiency.

In financial terminology it is called "Credit-Enhanced Capital Pool "and you can learn more about it and how the funds will be secured and managed by visiting this City of Toronto website: http://www.toronto.ca/city_manager/pdf/tr_implementation_book.pdf

In theory, as the cost of energy rises - the value of the bonds increases – and the value of the buildings is enhanced.

The City also intends to establish a “preferred supplier list” to promote local procurement of goods and services and develop training and employment programs as part of their over-all strategy.

If Toronto is able to move forward with this project there is no doubt that it would create an enormous opportunity for the all of the stakeholders involved in ownership, management and maintenance of the apartment buildings - and for the construction industry in general.

Overcladding retrofits

Energy efficiency was not a primary concern when these apartment buildings were built. The main focus, aside from controlling costs, was the speed of construction. With the timely invention of “slip form” concrete construction, the industry was eventually able to construct an average of 40 thousand units a year in the early 60s.

This activity continued until the mid-70s when condominium starts gradually increased and quickly garnered an increasingly greater percentage of high-rise construction activity.

At present, some 40 to 50 years later, the industry is poised to embrace overcladding methodologies for retrofits that have been deemed necessary to address performance problems that have been accelerated by deterioration.

This procedure is a practical remedy to rehabilitating building envelopes in tall structures that is achieved by constructing and fastening the cladding materials on the exterior face on all floors above the neutral axis: meaning above the height at which the overpressure in buildings due to the stack effect begins and increases to greater value with each ascending floor level.

The deterioration of the exterior face of upper portions of tall building walls is accelerated by the penetration of water from exterior penetration. At certain points in building envelopes, this water is also subject to freeze-thaw cycles which typically cause further deterioration.

Rainscreens wall systems

Overcladding retrofits involve the installation of rainscreen wall systems over the existing façade to prevent rain driven water from penetrating the structure.

This design approach virtually eliminates the risk of uncontrolled rain penetration which is achieved by intentionally leaving the joints in the façade open in order to allow air to move freely between the exterior environment and the interior cavity. This results in pressure equalization between the two cavities eliminates any forces that drive moisture into the system. Continuous air flow through the open joints also ventilates the cavity, preventing heat build-up and protecting the insulation and air barrier.

Improvements in HVAC systems improve the general condition of the indoor environment and the overall energy efficiency of the building.

Overcladding costs

An overcladding retrofit of a typical 20 story building requires an investment of several million dollars and although this appears to be a large investment, it is estimated that energy costs are cut in half. With many experts predicting the cost of energy will continue to increase, this consideration is an important factor.

The key performance issues are safety, stability, structural performance, acoustics, energy efficiency, air quality/ventilation, thermal and moisture movement, air permeability, cavity ventilation and serviceability.

For more information on what's going on in the Toronto apartment industry, check out Canadian Apartment Magazine.