Project overview:
Comprising two pairs of 2-bedroom semi-detached houses that meet the Nationally Described Space Standards, these pilot Passivhaus homes were built with noteworthy features to increase energy efficiency. The project had a significant M&E package of £136,629.08. A benefit of the scheme being procured through EEM was that a design development process could be completed with the client’s directly employed Passivhaus Consultant looking at efficiencies, buildability and value engineering.
Specialist features:
- A robust testing and commissioning plan was developed for the Passivhaus standards, namely:
- Air source heat pumps
- Solar panels and LED lighting throughout
- Mechanical ventilation heat recovery
- 48mm triple glazed laminate units
- Liniar 90mm Zero90 Casement windows
- Airtight to Passivhaus standards
- 300mm insulated cavity instead of 150mm
- Electric car charging points
- EPC rating: A
Collaboration between the contractor and client:
There was early engagement between the contractor and client as the project was put through a tailored cost plan that became a contract. Through weekly pre-commencement DTMs, a compliant design to meet the Passivhaus standards was designed, guiding the client and transferring knowledge. KPIs were realistically set with stretch targets; these goals were overall exceeded.
Social value:
The project engaged 714 students and provided 8 careers interventions, 3 work experience placements and 1 kickstart placement. Overall, £2.2 million has been generated within the local community, economy and environment. This figure is calculated through data entry throughout the project detailing measures such as local spend, locality of the supply chain and social value outputs. 80% of employees were from within 20 miles of the site, 90% of spend was within 20 miles and 100% of spend was with SMEs. Overall, for every £1 spent by Robert Woodhead Ltd, £2.84 was returned to the local economy. Robert Woodhead Ltd also achieved a 95% recycle rate.
Challenges and solutions:
Air-tightness testing
Seven critical Air Test stages were planned into the programme with our accredited supply chain partner (Focus Consultancy), including, watertight, pre-plaster, post plaster, pre-decoration and completion to meet Passivhaus standards at 0.6 air changes per hour. This identified opportunities to improve efficiency and reduce leakage at the earliest possible stage, preventing unproductive rectification works later in the programme. The team also hired air testing equipment to be able to monitor the building fabrics performance throughout the build programme as frequently as required.
Architectural details
There was collaboration between the client and the design team to ensure that architectural details or adaptations were modelled to still meet the Passivhaus standards.
Collaboration
There was good communication between the client and contractor to understand the process and reasoning behind these suggestions, with the client coming to site up to 3 times per week. Communication was also aided by a mid-contract review to address any delivery issues. Project sponsors were also allocated to sit outside of the operational team to speak to the client on a bimonthly or quarterly basis.
Testimonials
“The heating bills will be almost zero because of the way they’ve been designed and built. We’ve got the best insulation, we’ve got an airtight building, we’ve got mechanical ventilated heating systems. So effectively, the only thing that’s required to make these buildings work heat-wise is the heat of the sun and the heat of the people living in them.”
- Andrew Abrahams, Mayor of Mansfield
“I’ve been researching the Passivhaus design and it’s all very interesting. Being an energy efficient home means bills won’t be as high. I’ve always been really conscious about my carbon footprint. This home will help us contribute to the protection of the environment.”
- Carrie Green, tenant at Saundby Avenue