Glasshouse Group Limited SBE0086

Written evidence submitted by Glasshouse Group Limited

Glasshouse Group Limited was founded in 1991 and specialises in the development of managed mixed-use buildings, currently holding over 100,000 sq. ft. of freehold assets across eight sites in Central London.

In answer to questions:

The recommendation to use timber is not possible for many residential schemes due to the ban on ‘combustible’ materials in buildings over 18m and consequent problems relating to PI insurance for construction professionals.

Fabric performance in buildings is critical to the challenge of reducing operational carbon impacts. Plant based materials such as wood-fibre insulations and hemp bio-composites offer excellent thermal and vapour buffering, improving indoor air quality, reducing summer overheating, and minimizing the need for MEP systems.

Far more attention should be focussed on the domestic supply of plant-based construction materials. Industrial hemp for example can sequester carbon at a rate of 11 tonnes per year per hectare (compared to 4 tonnes per year for commercial forestry, taking decades to mature), whilst reducing the need for inputs and improving the yields of subsequent food crops.

Changes to planning policy and building regulations are the main drivers in delivering a sustainable built environment.

GLA policy consultations in respect of whole life cycle carbon and the circular economy have already prompted developers to formulate new strategies for development in anticipation of transitional arrangements. Likewise, future changes to the building regulations have required a reassessment of construction specifications and development costs.

It should be appreciated that, in the residential sector, these additional costs are not passed on to homebuyers (the price of a dwelling is predominantly determined by market conditions and the availability of finance). Rather, residual land values are constrained, though these values crystalise in the form of windfall gains, typically at a multiple of the pre-planning value.

On the other hand, the benefits of improved standards of air quality, thermal comfort and reduced operational costs pass directly to homeowners.


Developers need clarity to accurately price the value of development land, but there is no economic reason not to require more onerous planning policy and building regulations aimed at promoting more sustainable buildings.

RICS have published a detailed assessment methodology which can be applied consistently if policy makers choose to make it mandatory.


Some attention is paid to summer overheating, but existing passive strategies rely mainly on high thermal mass materials such as concrete and masonry, ignoring the hygrothermal advantages of plant-based materials.

It’s essential that technologies aimed at minimizing carbon footprint are properly assessed in relation to LCA

A dispassionate analysis of the operational and embodied carbon impacts should be undertaken at feasibility stage.

Nothing, other than to require a maximum permissible whole life cycle carbon limit (relative to floor area) by means of mandatory EPDs and a rigorous application of EN15978.


May 2021