The Triangle, designed for a brownfield site in Swindon, is the first phase of Grand Designs presenter McCloud’s plan to transform the UK housing market. Our client is Hab Oakus, a partnership between Hab and Westlea Housing Association, which is part of the housing group GreenSquare Group.

The 42-unit, 0.84ha development is described as a “contemporary interpretation of Swindon’s mid-Victorian railway cottages”, and comprises two-and-a-half storey terrace homes of between two and four bedrooms each, and ending in three-storey blocks of flats.
As the civil and structural engineers on the project, Curtins played a major role in the provision of sustainable solutions for the Triangle and introduced a number of cutting edge innovations to the project pushing the limits of conventional house-building expectations.

Drainage and Infrastructure
The drainage scheme for this project, in particular, is very unique. Not only did we satisfy the requirements of meeting the Code for Sustainable Homes’ Mandatory Surface Water credits incorporating Rainwater Harvesting to help recycle surface water from the roofs of all properties back into the dwellings to be re-used for toilet flushing, we also created additional rainwater storage sumps in strategic locations (adjacent to public spaces and the kitchen gardens) where any excess water from the roof is collected and stored as part of the site attenuation, and is available to be pumped by hand for resident’s use. Additionally, surface water from the adopted public highway is directed to a surface channel drain to the edge of the highway and diverted through swales to a central wet meadow where the area provides storm water attenuation. This water is then discharged off site through the underground drainage network and into the public sewer. This design solution enabled us to help reduce carbon use within the project by minimising excavations and drainage materials by managing the majority of the surface water on the surface of the site.  Curtins also successfully negotiated the proposal with the Local Authority to enable the integrated highway and drainage system to be adopted.

Low Carbon Superstructure
Curtins advocated the use of Hemcrete for the monolithic wall solution, which incorporated hemp grown specifically for the project. Using Hemcrete helps lock in CO2 during the growing process thus producing a negative embodied carbon value and also has a very low u-value and a high thermal inertia.  These properties result in a fantastic natural insulator delivering a fully recyclable material which assists with lower heating costs.  The Hemcrete was supported by a traditional structural timber frame which was constructed off an insulated suspended floor slab.

Material and Product Specification
Curtins also produced an enhanced specifica¬tion for products and materials for The Triangle which focused on recycled content and ability to be recycled. This process involved a comprehensive review of the current market to determine what items were avail¬able to the construction industry. The key items that were targeted included concrete mixes, paving slabs, tarmacadam, grass paving and water tanks.  Curtins optimised the materials and product specifications whilst ensuring there was no loss in performance or value, in an effort to minimise carbon wastage.