MULTIflow Thermal Store Meets Passivhaus Requirements

Passivhaus project

The MULTIflow thermal store was recently specified by Hawthorne Boyle in a 20 unit housing scheme, which was required to meet Passivhaus standards. Midlothian Council made a commitment that all of their new social housing would be to Passivhaus standard and ultimately set this out in its housing design guide.

The Burnbrae project in Bonnyrigg comprises of a two block development with a mix of residential and retail units, with all the residential units in both blocks are aiming for Passivhaus certification. The residential apartments are built to be ‘Passivhaus-ready’, with fantastic levels of air tightness and double-glazed windows & doors that may be upgraded later to achieve the Passivhaus standard.

Passivhaus is an international energy performance standard with buildings constructed to the Passivhaus standard reaching 30,000. Passivhaus buildings have been constructed in every major European country, Australia, China, Japan, Russia, Canada the USA and South America. The core focus of Passivhaus is to dramatically reduce the requirement for space heating and cooling, whilst also creating excellent indoor comfort levels. This is primarily achieved by adopting a fabric first approach to the design by specifying high levels of insulation to the thermal envelope with exceptional levels of air tightness and the use of whole house mechanical ventilation.


In a Passivhaus thermal comfort is achieved through use of passive measures listed below which can be applied not only to the residential sector but also to commercial, industrial and public buildings.

The MULTIflow thermal store provided the perfect hot water solution due to its excellent insulation levels and also hot water performance. Other thermal storage products were considered, however the MULTIflow was subsequently chosen as it met all the requirements of the specification team. One of these requirements was that the location of the hot water storage unit had no access to an outside wall, therefore an unvented solution that would require external discharge pipework was quickly ruled out. As a thermal store does not have this discharge requirement, it was able to be sited wherever the specifiers required.

Another requirement was the ongoing maintenance of the unit, which the client was keen to avoid. By utilising the thermal store instead of an unvented solution, this requirement was negated, saving Midlothian Council £1,000’s in future maintenance costs.

Click here for further information on the full range of thermal storage solutions.


Wayne Hyde

Product and Marketing Manager

Having been in the cylinder industry for nearly 20 years, in both product and marketing roles, I have extensive knowledge of all aspects of hot water storage, from domestic through to commercial applications, including vented, unvented and thermal store solutions.

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