Future Works (Welsh Passive Houses, Ebbw Vale)

 

A full case study of the Future Works project is available here. 
some_alt
These design drawings show Larch House's much higher glazing area (55% of the south side), compared to Lime House's 20% glazing ratio.

 

Project lead
Justin Bere

Building type, sector and stage
Social housing, post-construction, going into in-use monitoring. Wales.
 
Keywords
Passive House, MVHR, timber frame, airtightness, solar water heating, PV

Summary
These two timber frame homes were designed to achieve the very demanding Passive House standards but to cost no more than typical social housing. As the names suggest, ‘Larch House'(above)  is timber-clad externally, while ‘Lime House' has lime render. Both houses have solar water heating and solar electric panels on the roof.

Both homes have outstanding u-values: less than 0.1 W/m2K for walls, roof and floor. They achieved exceptional air-tightness, far better than the minimum requirements in current and proposed Building Regulations. Furthermore, they should both comfortably meet the UK Government's proposed 2016 ‘Zero Carbon Compliance' standard. Like other Passive Houses, they use heat recovery ventilation. The ventilation system works well, with low fan energy use, and no intrusive noise.
There were some problems with installing solar water heaters and adequate insulation for pipework, but these are now resolved.

There is now a comprehensive set of monitoring instruments in both homes, and tenants moved in in April 2012. Preliminary findings suggest that even in winter there is minimal heat loss when the ventilation system is off. At present the bedrooms are slightly warmer than other rooms, and air in the homes is a little dry when they are unoccupied. Both homes look set to have very low energy bills.
 The designers used very different approaches to designing windows for each home – driven by the weather data they used in calculations. Larch house has much larger windows and external shading (because of cautious assumptions about colder winters). Inevitably, this made it much more expensive to build.
There were some problems with installing solar water heaters and adequate insulation for pipework, but these are now resolved.

There is now a comprehensive set of monitoring instruments in both homes, and tenants moved in in April 2012. Preliminary findings suggest that even in winter there is minimal heat loss when the ventilation system is off. At present the bedrooms are slightly warmer than other rooms, and air in the homes is a little dry when they are unoccupied. Both homes look set to have very low energy bills.
 The designers used very different approaches to designing windows for each home – driven by the weather data they used in calculations. Larch house has much larger windows and external shading (because of cautious assumptions about colder winters). Inevitably, this made it much more expensive to build.

Key Performance Indicators

  Larch House Lime House
Floor Areas 99m2 78m2
SAP Ratings 112 (A) 97 (A)
Heat Loss Coefficient 60 +/-16 W/K 41 +/-8 W/K
Air permeability 0.26 m3/m2@50Pa 0.55 m3/m2@50Pa