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Tapping into hot water energy savings

Hot and cold water are at the top of the food chain when it comes to a homeowner’s hierarchy of needs. Of course, we need cold water for a host of day-to-day household operations like flushing toilets but hot water tends to be the real hero, so much so that tenants quickly take note of issues like long hot water wait times, sudden and rapid temperature fluctuations or when water is lukewarm but not hot.

That’s why immediate access to hot water is a top priority for building operations; it’s key to optimal tenant satisfaction. But sometimes things go wrong or building equipment is dated. In fact, 1/3 of energy used by a building is wasted due to existing issues and conditions in the water distribution system.

While many hot water issues are easily solved, most buildings don’t have any controlled way to improve water efficiency. This may be due to a lack of awareness of available energy-saving hot water technologies. Improving hot water delivery starts with raising the knowledge bar about how hot water delivery actually works and better understanding the needs of the end-user. 

So, how does it work? The process starts with cold water stored in a vat. When water is “requested” or needed, it empties out a bit for a boiler to heat. When it’s the right temperature, it circulates through a network of piping that runs upward into the interior of residential buildings. It acts kind of like a subway or an artery system. Hot water constantly flows through your pipes so it can be delivered immediately, instead of waiting for it to travel up 40 floors to your unit. So, when you turn your tap off, water recirculates to be re-heated by the boiler in order to maintain a consistent desired temperature. This method is called a recirculation system

Recirculation systems include mixing valves, which add in cold water to hot water so that it can be delivered at a temperature suitable for human touch but also ensures bacteria like legionella (often found in human-made water systems) can be effectively killed. Industry standards recommend hot water is stored at 140 ° F (60 °C) and then delivered in tandem with a mix of cold water so that it’s delivered through your taps at a desirable 120 ° F (40 °C). (recirculation system and valves)

The myth that buildings must store hot water at 140 ° 24/7 in order to effectively kill germs leads to a significant amount of hot water energy waste. New information states that as long as hot water stays heated for certain (shorter) periods of time, it can effectively remove germs from interior water systems. For example, keeping water at over 140 °F will kill germs as long as it is heated for more than two minutes, not 24 hours.

Among other things, water is still heated with natural gas – a fossil fuel. In order to maintain consistent hot water service, and improving a building’s overall property carbon footprint, it’s worth investing in smart controls in your boiler room. Adding smart technology like temperature sensors or pump controls can better streamline when hot water needs to be heated for different times of the day. For example, controls on heat pumps can heat water during peak showering times at 7 a.m. and then reduce heating at 2 a.m. when hot water isn’t in demand. By adding these controls, property managers can see a reduction in total heat loss by over 50% and total hot water gas use by 15%, turning heat lost into cost savings. 

Ultimately, improving the current hot water systems in place could lead to better greenhouse gas reductions, money in property pockets and happier tenants who can enjoy their hot shower and cup of joe in the morning whenever they need it.