The Low Carbon Eco House


The Low Carbon Eco House: The Pump House


Hurstpierpoint, Sussex


LCE Architects

Spray Foam Completion Date:

April 2021

Spray Foam Contractor:

Isotech Sprayfoam Ltd

Scope of Project:

Closed-cell spray foam insulation applied to a low carbon, new build to help it meet level 5 performance under the UK’s Code for Sustainable Homes


Elastospray LWP


Project Background

When planning permission for the Hurstpierpoint Pump House site, located in the South Downs National Park, was granted more than a decade ago there wasn’t a building that could be converted. The long-abandoned water authority pumping station consisted of little more than a borehole and some partially demolished Nissen huts.

However, planning permission was received under the predecessor of Paragraph 79 of the National Planning Policy Framework.  This meant that the design had to be of the “highest quality, truly outstanding in terms of its architecture and landscape design, and significantly enhance its immediate setting and wider surroundings”.

LCE Architects, a well-established design and consultancy practice of architects committed to producing buildings of significance that respect the environment and fulfill clients’ needs, were commissioned by the then-owner. Their brief was to create a detailed design for a carbon zero house that adhered to the UK’s then benchmark Code for Sustainable Homes.

Design complete and approved, the construction of the project then stalled.

Fortunately, when the site was sold with the planning permission attached, the new owner opted to proceed with constructing LCE’s pre-existing design.

Originally a level 6 Code for Sustainable Homes design, it became apparent early on in the project that it would be difficult to get builders to meet every requirement of the now superseded code. After running the design through the Passive House model, which almost passed, the planners agreed on a reduced requirement equivalent to level 5 of the code.

With a design, updated and aligned with current building regulations on sustainability, the newbuild eco home features low carbon performance as part of the project design throughout the ICF and timber build.

Already involved in the original design, LCE Architects supervised the foundation and superstructure build.



The Code for Sustainable Homes was introduced in England in April 2007. It was a voluntary national standard to improve the overall sustainability of new homes. The code, now superseded by new building regulations, provided a single framework within which the home building industry could design and construct homes to higher environmental standards. Consequently, the code also gave homebuyers information about the environmental impact of a property and its potential running costs.

In creating a low carbon home, LCE architects needed to factor in 9 different categories, contributing to an overall sustainability score for the home ranging from 1 to 6 stars. the 9 design categories span:

  • Energy and CO2 Emissions
  • Water
  • Materials
  • Surface Water Run-off
  • Waste
  • Pollution
  • Health and Wellbeing
  • Management
  • Ecology

The primary objective was converting the site of an old water pumping station into a home that fulfilled the client’s desires for a naturalistic experience and the demands imposed by the principles of low carbon emissions.

The curved (in plan and elevation) design created various challenges. The ceiling was constructed using joists laid out like the spokes of a wheel (spaced more narrowly at one end than the other). The roof deck rested on the joists and on top of the perimeter walls. This meant that using rigid insulation would have been a time-consuming and labour-intensive exercise but more importantly, would not have easily provided sufficient insulation (with sub 5 GWP score) under and between the solid joists to maintain the required U-value and ensure a sub 1.0 ACH airtightness value.


The Solution

The owner and project manager contracted Isotech Sprayfoam Ltd, expert spray foam contractors, to install BASF’s Elastospray LWP spray foam insulation at a depth of 300 mm to optimise the thermal insulation of the timber pump house ceiling spanning 270 sqm and achieve the required Low Global Warming Potential score of less than 5.

Quick and easy to apply, the high-density, closed-cell polyurethane foam generated little mess and had an immediate impact.


The KIWA certified foam expanded into the timber stud work roof cavities to create a seamless, airtight fill, preventing air leakage and air infiltration and helping prevent condensation.  Without the need for laborious cutting and fitting of insulating material, Elastospray LWP allowed a complete foam seal, of consistent thickness, that achieved the preferred u-values specified.

Elastospray LWP is hypoallergenic and contains no fibres, dust, or noxious vapours. With no VOCs, CFCs, formaldehyde Elastospray LWP has no harmful side effects and doesn’t contribute to global warming.

With the BASF Elastospray LWP spray foam installation now in place, experts are continuing to complete the exterior.   Upon completion, The Pump House promises to be a quite remarkable grand design and a testament to the dedication, vision, and skills of all those involved in this low carbon, eco home.


Client Testimonial

‘I was delighted with the end result. I project managed the entire build and was responsible for sourcing all the trades and materials to ensure that they complied with the CfSH requirements. Not a builder by profession, I particularly valued the level of support I received from Econ throughout and ahead of the construction phase.  Isotech were friendly extremely professional (producing work to a very high standard) and importantly delivered on time and on budget.’ 

John R. – Owner


Further Information

Find out more about the install on this project from a contractor perspective by visiting Isotech Sprayfoam Ltd’s dedicated section on architectural specifications here.

If you need technical assistance with your project, ECON polyurethanes would be delighted to get involved once you have completed our project contact form.




Share this post

Share this post

error: Content is protected !!