6. Affordable We need to be cost-competitive compared to alterna- tive solutions. Therefore, we prefer the use of standard (mass-produced) components. To reduce installation costs, field modules are preassembled by design and transported to the site.
and delivery. Very large heating surfaces such as under- floor heating are preferable, which can be done with a reasonable cost in newly built houses. Not so in existing housing, where the cost of underfloor heating would of- ten be prohibitive. We aim to use existing radiators and employ control technology to operate at the most effi- cient temperatures for cost reasons continually. Furthermore, too low-temperature difference distribution systems are impractical and costly, and we need to sup- ply domestic hot water, which requires somewhat higher temperatures of around 60°C. The lowest return tempera- ture possible optimizes transportation. As it happens, this fits well with an array of heat pumps once you connect those in series. We run the array as close to 60°C as weath- er permits, while every degree of lowered return tempera- ture improves array efficiency. In our first implementation, the array consists of 10 heat pumps supplemented with natural gas-fired boilers with 1.5x heat pump capacity, in series with the heat pump array. This allows us to reduce the heat pump supply temperature further once boilers are needed. 4. Modern Control of DH equipment in homes is usually done with passive regulators, which cannot connect to apps on mo- bile phones. We need active (electronic) components to optimize function anyway, which opens a pathway to modern user interfacing. 5. Connected Heat meters are required to be connected by law, neces- sitating some channel of communication. This channel allows for firmware upgrades, which we made a require- ment for control equipment.
Conclusion DH is an essential tool in transitioning from natural gas to sustainable heat sources in existing houses. This transition can only be made with a cooperation-based, community approach and a modular technical system approach.
7. Upgradable
Having toomuch ambition for the time available, we were forced to run design teams concurrently on assumed op- erating conditions, having to settle for less than perfect in the process. We chose to promote this drawback to the guiding principle: the first edition will work, the next one will be better. Wherever possible, we design for up- gradable solutions, which are the easiest in software. With production fully operational and about half of the houses connected, we see ample room for improvement.
For further information please contact: Roelof Potters, roelof.potters@alliander.com
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