Case Study: Whinfell Drive
Case Study: Whinfell Drive

Code Level 3
Whinfell Drive, Kendal
5 x Housing Association Bungalows
Background
Impact Housing Assocation are a Cumbria-based company with long-standing links with Thomas Armstrong Construction Ltd.
As with all public sector / social housing, building to meet Code Level 3 of the Code for Susitainable Homes became mandatory in 2008 which requires a 25% improvement in energy efficiency compared with the standards of Part L 2006.

The initial specifications and designs were based on timber-framed constructions until the possibility of using solid Airtec aerated block walls with a rendered external insulation system was explored. This is the Super-Insulated Masonry (SIM) wall construction.
Detailed costing exercises and technical research confirmed that:
- The SIM construction would be significantly cheaper (approx 15 - 20% saving).
- Would achieve better U-Values than the framed option using the best block avaliable in terms of thermal conductivity (Airtec XL - 0.09W/mK).
- Would be quicker to build, employing the speedy and efficient Thin-Joint blocklaying method.
- No lengthy lead-time; blocks can be delivered and used as required.
- The homes would benefit for decades from the Thermal Mass effects of a heavy masonry building
- Airtec floor blocks and Airtec block internal walls means single-sourcing of materials
Taking all of these considerations, and other advantages as outined on the
SIM Wall information sheet, it was clear that this was the easiest and most cost-effective solution for this project.
For this project, iInstead of the 150mm of external insulation (to give a U-Value of 0.14), the insulation thickness was reduced to 125mm to give a U-Value of 0.16 as this would more than satisfy Code Level 3 and represent even more cost-saving for the client.
The Bungalows

Specifed to Code Level 3, the overall construction is:
- Ring beam foundations
- Block and Beam floors using Airtec Large Format blocks as infill (U-Value 0.12)
- Airtec XL 2.9N, 190mm solid external walls using Thin-Joint mortar
- 125mm Neopor insulation (to give an overall wall U-Value of 0.16)
- External reinforced render system
- Airtec XL 2.9N internal walls
- Timber truss roof (U-Value 0.10)
- Windows with U-Value 0.80
- Hot water bolier with > 91% efficiency
- No solar or PV required to meet the code
- Airtightness 4.0m²/(h.m²) or better