Exemplar office retrofit
The Voreda House project has seen the transformation of 1950-60s municipal offices in Penrith into a state-of-the-art EnerPHit certified council building for Westmorland and Furness Council.
A complex retrofit project, Voreda House is the first council office retrofit to the EnerPHit standard in the UK and offers valuable lessons for similar typologies.
Strategy
The Voreda House project has seen the transformation of 1950-60s
municipal offices in Penrith into a state-of-the-art EnerPHit certified council
building for Westmorland and Furness Council.
A complex retrofit project, Voreda House is the first
council office retrofit to the EnerPHit standard in the UK and offers valuable
lessons for similar typologies.
With a treated floor area of 1400m2, the project involved retention of the original concrete frame of the office buildings. The building was wrapped in insulation externally to improve the offices thermal performance and comfort. The pre-cast concrete roof was overlaid with insulation and the concrete panelling on the outside of the building was removed and replaced with a steel frame system which holds a carrying panel with stone wool insulation to insulate the building externally.
The external wall insulation (EWI) was extended down into the ground to minimise thermal bridging at the building’s foundations. The original office building had an undercroft which was brought within the thermal envelope to improve the building’s treated floor area and simplify its form factor.
Air-source heat pumps provide heating and cooling to the building. Roof solar panels are estimated to generate a third of the building’s energy requirements.
Project team
Client: Westmorland and Furness Council
Contractor: Collinson Construction
Passivhaus Consultant: Greengauge
M&E Design: Pettit Singleton Associates
Architect: 2030 Architects
Passivhaus Certifier: Etude
Key data
“Retrofit projects are always a challenge. They need to be designed to achieve realistic levels of efficiency within the limitations of the existing structure. Not every retrofit can achieve Passivhaus or EnerPHit levels of performance but when the opportunity presents itself it just makes sense. “
Paul Smith, Director, Greengauge
Challenges & solutions
Working with an existing building inevitably results in challenges for the project team:
· Structural issues with the building’s concrete frame were uncovered during construction, and needed to be rectified.
· The building’s stairwell and lift shaft were structural and could not be demolished so needed to be wrapped with external wall insulation to minimise thermal bridging.
· The floor to ceiling height was constrained which meant that adding ground floor insulation was difficult. Space-saving insulation was required for the floor of the existing building. The installation of the ventilation ducting on low ceilings was also challenging.
· There were limited options for penetrations for services, such as ventilation, and penetrations through the existing roof were structurally not possible. To address this an external service zone was created and the ductwork drops were run external to the thermal envelope.
· Using a steel frame system to hold the EWI system created additional thermal bridging issues, which needed to be carefully modelled.
· Designing a ventilation system to cope with the building’s varying occupancy rate and different room layouts (cellular on ground floor and more open plan on upper floors) was also an important requirement for the project.
“Having the first UK retrofit building of this type to gain Passivhaus EnerPHit certification within our portfolio of assets is a massive achievement for Westmorland and Furness Council. It reflects our ambition to manage our buildings in a modern, positive, and environmentally efficient way.”
Cllr Peter Thornton, Cabinet Member for Highways & Assets
