River Street

on Monday, 31 March 2014. Posted in Passivhaus New Build Projects

Green Box Associates have been working with First Wessex, Kenn Scadden Architects and Warm Associates to design 4 certified Passivhaus town houses in the heart of Portsmouth.

A small block of flats have been demolished in Somerstown and are to be replaced with 4 certified Passivhaus’ and three bungalows.


River Street Portsmouth  

The three bedroomed houses have been designed to achieve both the Passivhaus standard and level 5 of the Code for Sustainable Homes.

The homes are build using traditional cavity construction with 250mm Isover 3CWS 2 batts to achieve both low values and continuity of insulation. Air tightness to be achieved by parge plaster ,taped OSB and proprietary membrane and tapes. The triple glazed windows are both Passivhaus certified and secured by design.

Initial modelling in PHPP ( Passivhaus planning package) shows that the houses will have a heating demand of 15 kWh per m2/a and a heat load of 9W/m2


PHPP modelling 

Green Box Associates provided the following services to assist with the build.

  • PHPP modelling
  • Design and product advice to achieve Passivhaus and Code level 5
  • Code for Sustainable Homes assessment
  • NHER SAP assessment
  • Sustainability and Energy Statement
  • U value calculations

Key features to achieve Passivhaus

  • Low U values Wall 0.11 W/m2k, Floor 0.14 W/m2k roof 0.11 W/m2k
  • Paul focus MVHR unit
  • Small combination gas boiler
  • Triple glazed windows
  • Cross ventilation and shading

To find out more please call us at on 02392655652 or email   This email address is being protected from spambots. You need JavaScript enabled to view it.