How to Build a Green Condo Part II: “Tunneling through the cost barrier”

Thanks to the Toronto Green Standard, Toronto has the most progressive energy efficiency standards for new buildings in North America. Yet even these ambitious standards only scratch the surface of what is achievable at zero incremental cost!

Sound hard to believe? The trick is taking a holistic design approach which has been described as “tunnelling through the cost barrier” (Natural Capitalism, Lovins et al., 1999). While each individual energy efficiency measure has a cost, by combining enough measures into a project, you can often reduce or even eliminate the need for major building components. The classic example is insulation; while each additional unit of insulation costs money and delivers declining marginal returns, if you add enough insulation you can reduce the size of the heating equipment — thereby saving more than the cost of the additional insulation.

Our latest TowerWise case study provides a great example of tunneling through the energy efficiency cost barrier. Appleby Woods is a recently built, 101 unit condominium developed by Del Ridge Homes in Burlington, ON. The building uses less than half the energy of a typical condo (10 ekWh/ft2), yet cost about 25% less to build. The foundation of this remarkably efficient design is the use of Insulated Concrete Form (ICF) construction. Essentially, its concrete sandwhiched between highly efficient styrofoam insulation. The R45 insulation extends all the way down to the parking garage — allowing the developer to avoid the cost of installing a heating system for the garage.

The excellent insulation and thermal mass provided by the building envelope  made it economical to provide 100% of the building’s space heating and cooling through a ground-source heat exchange (aka geothermal) system. The cost of drilling 54 boreholes for the geothermal system was offset by the avoided cost of conventional heating boilers and associated venting systems and natural gas lines.

The building’s surface parking lot is lit by solar-powered LED light fixtures. While either solar lights or LED lights would have been an added cost, combining the two together was possible at zero incremental cost. The efficient lights meant that the solar panels and batteries could be smaller, and the solar system avoided the time and expense of digging trenches and burying power lines to connect each light fixture to the grid.

The savings from combining the ICF envelope with geothermal heating and cooling allowed the developer to include a 30KW solar PV system on the roof, while keeping the total cost of the building below average.  The solar PV system has a Feed In Tarrif contract which provides about $22,000 per year in revenue to the condo corporation, helping to keep monthly fees in the building well below average.

There are a host of other efficiency measures as well, from motion sensor lighting to low-flow toilets. You can read about them all by downloading the full case study from  But the bottom line is that this case study challenges us to rethink some really basic assumptions about the “cost” of energy efficiency. While each individual green feature has a cost, by taking a systems approach and pushing the envelope it really is possible to deliver higher performance at less overall cost.


This entry was posted in Advanced lighting, Energy efficiency, General, High-rise energy efficiency, Solar Energy and tagged , , , , . Bookmark the permalink.

2 Responses to How to Build a Green Condo Part II: “Tunneling through the cost barrier”

  1. Lisa King says:

    Does TAF have information supporting the fact that Toronto’s EE requirements are leading in NA? We would be itnerested in seeing this. Our focus was on raising the bar to achievable, cost-effective levels. Do you agree that by increasing the performance metric alone that one fosters “Tunneling” or is there more involved in the concept that requires setting out a suite of building measures and targets that are more prescriptive in nature? Thanks for the post, Lisa

    • Bryan Purcell says:

      Hi Lisa, my assessment that TGS has the leading EE standards in NA was based on a comparison with other leading codes, such as California’s CALGreen standard. If you know of any other NA jurisdictions which have set the bar higher please let us know!

      Energy performance standards do encourage ‘tunneling’, but cannot gaurantee it of course. Its more about the process of designing the building than about any specific measures. For example, if different individuals are involved in designing the envelope and the HVAC system, they don’t neccessarily see the opportunity to achieve savings in the HVAC area (smaller/fewer boilers) through a better envelope. An integrated design process can help identify these kinds of synergies.


Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: