Passivhaus Affiliate

Electrifying Somerset Passivhaus Plus Primary completes

The all-electric Two Rivers Primary School in Somerset sets a new benchmark for future Passivhaus schools. On-site renewable energy generation is predicted to surpass its annual energy consumption.

Two-Rivers-Passivhaus-Primary © Bhagesh Sachania Photography

The commitment to Passivhaus Plus was implemented during the design phase, aligning with the local council's commitment to tackling the climate emergency.

A clear airtightness strategy and a centralised air handling plant were crucial to delivering Passivhaus Plus. Certification was awarded by PHT Patron WARM  with PHT Patron Max Fordham, acting as Passivhaus consultant.


Key stats

  • Construction: Steel frame

  • TFA:  1821 m2

  • Number of occupants: 420 pupils   

  • Build start date: 2021

  • Completed: 2022

  • Certified: Passivhaus Plus

Two-Rivers-Passivhaus-Primary © Bhagesh Sachania Photography


Two Rivers Primary School Quote Card Max Fordham © image Bhagesh Sachania Photography



Two Rivers Primary School is built using a traditional steel frame, concrete floor slabs and brickwork external walls. The ground floor is built from light buff brickwork, with white render above. High-quality dark grey aluminium windows and a dark grey roof are off set by strategically placed walls of local blue lias stone. 


Ground Floor Wall: 0.146 W/m2K

6mm Render, 230mm Mineral wool, 10mm Adhesive, 13mm Siniat weather defence, 250mm Steel frame void, 15mm plasterboard

First Floor Wall: 0.213 W/m2K

Brick wall, 175mm Mineral wool, 13mm Backing board, 250mm Steel frame void, 15mm plasterboard


Under-Construction Concrete Planks - Two-Rivers-Passivhaus-Primary © Hatcher Prichard Architects Under-Construction Steel frame - Two-Rivers-Passivhaus-Primary © Hatcher Prichard Architects
Under-Construction Blue Lias Stone Two Rivers Primary School © Hatcher Prichard Architects
Under-Construction Render Base Two Rivers Primary School © Hatcher Prichard Architects
Two Rivers Primary School under construction - Concrete planks, steel frame, blue lias stone, render base


Building performance

Designed energy performance 

Airtightness n50 (≤ 0.6ACH @ 50 Pa)                           


0.391 ACH


Space Heating Demand (≤ 15 kWh/m².a)


7 kWh/m².a  


Heating Load (≤ 10 W/m²)


7 W/m²


Primary Energy Demand (≤ 120 kWh/m².a)


149 kWh/m².a


Primary Energy Renewable (PER) Demand (≤ 60 kWh/m².a*)    


59 kWh/m².a


Primary Energy Renewable Generation


87 kWh/m².a


*+/-15 kWh/m².a allowance if offset by energy generation. See Passivhaus criteria


Department for Education (DfE) schools typically have mechanical air handling units installed in every classroom, but modelling revealed that this would result in too much heat loss to achieve Passivhaus Plus. As such, the school has an intelligent MVHR composed of a single large centralised air handling unit that promotes the natural movement of air throughout the school within a carefully curated system of ducts.

The design ensures a comfortable temperature of 20 degrees Celsius with air source heat pumps (ASHP), underfloor heating, and 'kiddie watts' - body heat from 420 pupils. It is complemented by on-site electricity generation from over 200 PV panels on the roof. 

Solar panels on Two-Rivers-Passivhaus-Primary © Hatcher-Prichard-Architects_
Ventilation Two-Rivers-Passivhaus-Primary ©  Bhagesh Sachania Photographytects_ Ventilation and services Two-Rivers-Passivhaus-Primary ©  Bhagesh Sachania Photographytects_
Two Rivers Primary School services

Lessons learned

Over 500 hours of training were delivered, successfully upskilling the supply chain on Passivhaus accreditation. It will influence further DfE school design. Collaboration between all stakeholders and the supply chain partners was the key to successfully achieving air tightness of 0.391m3/h/m3.

The architects highlighted the transferable nature of Passivhaus requirements and better detailing to other projects. They are working closely with the contractor to incorporate the enhanced design & detailing of the project into all future schemes in line with their net zero-strategies.

Two Rivers Primary School Quote Card Hatcher Prichard © image Bhagesh Sachania Photography

The contractor praised a greater degree of cost certainty early in the project than they would usually have, spurred by the detailed Passivhaus design. All parties working toward a shared goal and measurable targets facilitated a highly collaborative environment.

Two Rivers Primary School Quote Card ISG © Image Bhagesh Sachania Photography

Key team 

  • Client: Department for Education (DfE)

  • Architect: Hatcher Prichard Architects

  • Passivhaus Consultant: PHT patron members Max Fordham

  • Contractor: ISG

  • M&E consultant: Hydrock

  • Passivhaus Certifier: PHT patron members WARM

Two-Rivers-Passivhaus-Primary © Bhagesh Sachania Photography

This was the first Passivhaus project for the many of the stakeholders involved. Congratulations to the whole team & Hatcher Prichard Architects for embracing Passivhaus and delivering this wonderful Passivhaus Plus Primary School.


Similar projects 

The projects below are all Passivhaus-certified educational buildings. Discover more projects on our Passivhaus Schools & Educational Buildings or the Plus & Premium pages. For more guidance, check out the How to Build a Passivhaus: Good Practice Guide or our FREE technical guidance on Steel in Passivhaus Construction.

Passivhaus Plus St Edwards School Hampshire
Passivhaus Thornhill Primary School
Passivhaus Plus Hackbridge Primary School


Further information

Two Rivers Primary School

Passivhaus Educational Buildings Case Studies

Technical Guidance - Steel in Passivhaus Construction

Passivhaus & Zero Carbon

Passivhaus for Educational Buildings Campaign

PHT guidance: Qualiity Assurance for large & complex buildings

Passivhaus Net Zero Primers

Passivhaus Benefits Guide & costs research 

Passivhas Plus & Premium projects

15th February 2024

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