International symposium of CIB W062

Challenges in building installations around the world – temperature

Designing water supply and drainage in a building requires knowledge on water demand (and discharge), not just the amount but also the temperature and health related water quality. In order to prevent growth of pathogens such as Legionalle, the cold water temperature must be kept below 25, and some said 20 °C; hot water temperature must be kept above 55, 60 or 65, depending on the country and residential or non-residential systems. This is a challenge as many participants stated that the water temperature coming in from the drinking water distribution system is in many cases already at 23 or higher, and will get warmer in warm buildings (heated in winter, or not cooled below 25 °C during summer). Mr. Petzolt rom Kemper (Germany) showed an innovation in thermal mixture taps that ensures the cold water pipes are not affected by the hot water supply. Mr. Bleys from BBRI (Belgium) showed that a thermal shock of 60 degrees was not enough for thermal disinfection, and that the hot water tank needs to be properly mixed to ensure the whole tank is heated to the required temperature.

Challenges in building installations around the world – pipe sizing

Each country has their own design rules, installation codes etc. to determine the best size of pipes and tanks, based on expected (maximum) water demand. Many of the country specific equations for maximum water demand have been around for decades, and the rationale for them are nowhere to be found. Under which circumstances are they applicable? Many participants believe there is a need for new equations, since households have much more access to hot water, have decreased in size, are installing more water saving appliances. And this also holds for non-residential buildings. Many initiatives around the world are starting, many based on measurements. Mirjam Blokker from KWR showed in her keynote speech that stochastic demand modelling is a very good alternative to reach the new equations for maximum demand. SIMDEUM was developed and validated for residential and non-residential use in the Netherlands. SIMDEUM was then used to derive “rekenregels” for the drinking water installation, which are since a few years in the official guideline ISSO 55. Discussions during coffee breaks and over lunch showed me that convincing the national committees on the one hand of doing something innovative like modelling (instead of relying on measurements) and introducing new guidelines that require not just counting fixture units, nut also taking the users into account and on the other hand of using something that others have invented is not always easy.

The participants seemed to be all part of one big family, and there seemed to be many people willing to cooperate and learn from each other. I am certain this will lead to new innovations.

Keynote speech by Mirjam Blokker.