Building designers will be obligated to create durability plans for new structures once new climate change standards are incorporated into building codes across the nation, some time after 2020, a Toronto Buildings Show workshop was told recently.
Workshop leader Gerald Genge, an engineer with Pretium Consulting Engineers of Burlington, Ont., laid out changes that will be incorporated into the National Building Code (NBC) in 2020 and beyond to address building life in the face of harsher climate conditions.
Genge recently led a committee of building science experts tasked with converting Canadian Standards Association (CSA) guideline S478 on durability in buildings into a new building code standard.
The committee began meeting in August 2017 and has produced its work in “record time,” said Genge.
“In 2020, we are doing the administrative change, to change the word from guideline to standard,” he explained.
“The standard includes the obligation for designers to create durability plans, and the durability plans have to be based on the life of the building, the life of the components that go into the various envelope components of the building, and the elements that are part of those components.
“The example is, we don’t want to have buried sealants inside a wall system that fail before the wall does.”
National Building Codes are developed by the Canadian Commission on Building and Fire Codes and published every five years by the National Research Council of Canada (NRCC). Provinces and territories study the new elements and consult with stakeholders and experts with a view to determining which measures will be incorporated into the building codes for their jurisdictions.
A federal auditor general’s report in 2016 was critical in observing that the current approach to building design was based solely on historical data and does not reflect climate change trends. Climate loads in the NBC are currently derived from 50-year data. The NRCC agreed with the report and is now co-ordinating the new initiative with Environment and Climate Change Canada (ECCC) and the CSA.
“Building design requires predictive data,” said Genge. “It is now being considered as a mandate of the National Building Code. And if it’s a mandate of the National Building Code, it is going to end up in every province’s legislation.”
Genge said incorporating durability in response to climate change represents an expansion of the mandate of the code from its original purpose of ensuring health and safety and structural sufficiency.
“In the future, they are going to have to think about the life of the building and design systems and components and elements that are in the building envelope, for instance, to withstand future climate load,” Genge said.
The changes to the building code will come in two stages, said Genge. The committee is instructing designers in creating the durability plans, which is part of step one. But what is required to make the process effective is good data from ECCC, he explained.
“What we are looking for from ECCC is that we get the data put into the national code so that we as a standard-writing body can say, use this data, and use it in this way,” said Genge.
“Step two is coming when we get the data. We want to give them a foreshadowing of what they are going to have to learn about down the road.”
The presentation walked delegates through the current state of weather science, with lots of good data currently available on temperature trends, lesser quality data on general precipitation and snow, and poor data on wind, wind-driven rain, freeze-thaw cycles, severe ice storms and UV radiation.
Genge noted some stakeholders have asked why the predictive data won’t be incorporated into the code until 2025.
“It’s because we just don’t know the answer yet as to what future loads are going to be,” he said. “There is a lot of modelling done but we don’t know what building designers should use, we don’t know every climate impact yet. So it requires a more cautious process than just pulling a switch.”
Genge said he did not think the new responsibilities for architects would be too onerous.
“I don’t think it is a significant change to their process,” he said. “All they really have to look at is not only how things fit together but how things come apart.”