HOT|COOL NO.4/16 - "From one generation..."


By Pernille M. Overbye, Managing Director, District Energy Systems Canada, Ramboll

The benefits of hot water vs. steam can be summarised as, but may not be limited to, the following:

Universities and colleges throughout North America are increasingly looking at their energy and maintenance costs. A number of them are considering a hot water district energy network either as a replacement for their existing and old steam system or as a new system. A driver for looking at direct energy is in some cases a genuine wish to be more efficient, reduce energy consumption and CO2 emissions. However, often increasing and deferred maintenance charges are not only a driver but also an opportunity. Benefits of converting from steam to hot water Many universities, colleges and medical campuses in both the US and Canada have a district energy system in the form of a steam system, and it is also seen in some cities old downtown areas. Many of these systems are very old. The oldest continuously operated commercial district heating system in the world is in downtown Denver, Colorado where the steam service began to the first customers of the Denver City Steam Heating Co. on Nov. 5, 1880. Often steam was employed because of the focus on electricity, and in reality, the steam was in some cases distributed so that electricity could be generated locally in the connected buildings. Electricity seems to still be at the focus in North America and this is by default what most people think of when energy is on the agenda. To change from steam to hot water will therefore require a significant change in mind-set and core energy system, not to forget substantial changes in the buildings’ secondary systems. In spite of this, the opportunity arises as many systems have not been accurately maintained and often the city system operator, the college or university realises that to keep the system going, huge investments are required. Also, the realisation that a vast amount of the energy, sometimes in excess of 25 % is wasted in the distribution of the steam alone brings the opportunity for hot water on the agenda.

• Lower investment costs • Lower operating costs due to lower temperatures • Significantly lower maintenance costs • Higher efficiency for the entire system • Lower heat loss 5-15 % vs. 25-35% for steam • No steam traps, condensate return etc. • Lower temperatures enable access to a broad range of renewable sources • Enables thermal storage to be utilised • Higher flexibility in operational strategies and security of supply

Figure 1 - Steam explosion at Manhattan 2007

Leading US campuses are doing it A number of universities and campuses in the US have, or are, already converting their steam systems. The work can often be done in phases; the opportunity could be through a new campus building or the re-development of an entire area of the campus. Also, as the hot water network more often than not will require new pipes, the network can be installed one year, and the conversion and connection of the individual buildings can follow the next. In this way, the investment can be phased and the interruption to services better controlled. Some of the US campuses that have or are converting their steam systems are:

• Dartmouth College, NH • University of Texas, Austin • Massachusetts Institute of Technology (MIT), MA • University of Washington, WA • Stanford University, CA

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