Design for reliability – Consider climate change
September 20, 2021
re·li·a·bil·i·ty, /rəˌlīəˈbilədē/, noun, The quality of of performing consistently well.
re·sil·ience, /rəˈzilyəns/, noun, The capacity to recover quickly from difficulties; toughness.
When engineering for the built environment, Associated Engineering considers reliability and resilience for the systems we design. We include safety factors, stand-by and back-up process systems, alternative feeds, and back-up power to mitigate risks, such as climate change impacts. Adding redundancy to our systems is one way to achieve resilience, but redundancy has impacts, such as increased cost, maintenance, and embodied carbon. Designing for climate resiliency goes beyond ‘n+1’ and requires discussions with owners and operators. We need to think “outside of the box” and the facility we are designing.
Power Supply: Floods, snow, and fires can destroy critical infrastructure, leaving facilities without power for days, weeks, or longer. Fires may require the shutdown of natural-gas-powered systems. Adding a back-up power generator is a solution; however, we must consider the source of fuel for generators, the facility’s location, and the risks associated with fuel supply and transportation. Transportation routes can become blocked or damaged in flood events, blocking critical supplies.
In the past, for cold climates, we have specified arctic-packages for outdoor generators. With the changing climate, we are experiencing +39°C temperatures in locations like Edmonton, Alberta, so we also need to consider high-temperature radiator and coolant systems so that we can operate up to +40°C. We also consider air conditioning in generator rooms. Care must be taken to consider the additional building electrical load which the generator has to power. And, the generator has to be sized to power the cooling for itself!
Too hot to handle: In the past, when designing facilities in Canada, electrical designers didn’t worry too much about the ambient temperature; that was a consideration for the building mechanical designers. However, the Canadian Electrical Code for cable sizing is based on +30°C. Equipment that is rated for +30°C will need to be in a conditioned space. Equipment that is rated for +40°C may also need to be in a conditioned space if there is a lot of heat accumulation in the area.
We may need to consider multiple distribution systems and shedding power, because the equipment may get too hot or overload the generator. Maybe we need to design for full normal operation up to +30°C, only essential equipment from +30°C to +40°C, and for critical systems to operate when temperatures are over +40°C.
Recovery: After fires and floods, we have faced questions such as, ‘How hot did the conduit get with the fire being so close?” or “Did the smoke enter the building and cover copper with soot?” Considering potential fires, stickers can be applied to conduits; the stickers change colour if the outside temperature rises to +90°C. Then, operators and designers know the wires were compromised and need to be replaced. We can add smoke detectors in electrical rooms; if the alarms activate, we know there may be soot inside the room. However, smoke detectors are not precise, and don’t identify conduits drawing smoke directly into panels or motor control centres. After flooding, all affected electrical systems need to be replaced, which can be a significant cost to owners.
Engineers must consider future flood levels when designing new or renovating facilities. The changing climate creates impacts we must consider to reduce risks to facilities. Designers, owners, and operators need to have candid discussions so we can make informed decisions and develop reliable and resilient systems.
About the Author:
Scott Friel, PE, P.Eng. is an Electrical Specialist in our Edmonton office. He has 24 years of experience in electrical systems design, electrical inspections, certification of hazardous location equipment, and commercial and industrial engineering studies.