Harpenden Passivhaus

Contract Value
Circa £750k
Project Description

We are building a replacement dwelling on the site of an old bungalow. The new-build will be an all-electric timber frame 4 bedroom Passivhaus Plus using the ‘homes as power stations’ concept. This means it generates much more electricity than it uses and it can operate ‘off-grid’ without need for grid electricity supply for much of the year, saving any excess in its battery system and further excess sold back to the grid. It affords the occupiers a warm and comfortable environment with constant fresh air. The designers bere:architects also designed our RIBA award-winning project Max Fordham House.

This property is also one of the first installs in the UK of a Pichler PKOM4 fully integrated 2 stage air source heat pump hot water cylinder with MVHR, heating and cooling through air, (air to air), heating through water (underfloor) and hot water as one item. It has been integrated into the Loxone smart home system. The property takes its water from a well and has a huge rainwater harvesting tank which supplies toilets and the washing machine. A 3 stage waste water recycling centre was installed to treat sewage. The resultant ‘grey-water’ is used to irrigate the garden and surrounding fields.

Light and heating sensors in the house communicate with the smart home system which automatically operates the external shutters on windows to regulate internal temperatures. Installing a sprinkler system in a timber frame house also brought complications and required integrated auto water shutoff with four water sensors around the house. If any of the bathrooms or utility room leak water, it auto shuts of water for whole house to prevent damage to the timber frame or insulation.

  • “Passing our air test the first time is testament to how well Bow Tie do things”

    – Justin Bere
  • “Bow Tie are meticulous in how they do things”

    – Justin Bere
  • “Rafael is very familiar with the latest building technologies and is always on hand to offer suggestions and advice on the practicalities of achieving the desired end product.”

    – Brian A
  • “We’re expecting a dramatic reduction in costs. We now know how much energy we’ve used (in March) and we rarely have the heating on compared to this time last year in our old house.”

    – Toni M
  • “My projects with Bow Tie are the only ones where I’ve left the contractor to follow my airtightness details and the projects have passed the 1st airtightness test.”

    – Justin Bere

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