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Wondering how to further reduce your energy bills? Have a look at the HOBBS report for a few ideas.

Friday, July 20, 2012

Achieving air tightness

After the first air tightness test at the 1950's refurb (see previous post), we were very honoured to have a visit from Bill Butcher, Director of the Green Building Store. Bill has many years of sustainable building experience and was one of the team working on the world's first Passive House with cavity wall construction (in Denby Dale).

Bill spoke about his experiences of low energy building projects to a gathering of sustainable builders (AECB members). The discussions focused on achieving air tightness, and the 1950's refurb provided many examples of areas that present challenges!

To name a few: round the windows and doors, round pipes and cables, up through the edge of the floor, through the walls where plaster is missing / cracked, round the joists, at the eaves, and almost anywhere in the loft conversion!

Over the next few weeks, we'll be working hard to banish all draughts - with progress updates from time to time at

Wednesday, July 18, 2012

Air tightness testing

As part of the "Homes Behaving Badly" project, 4 local homes received air tightness testing. The results from these 4 case studies can be found in the HOBBS Report.

Two further case studies were tested by Midland Energy Services just last week, and the results are in!

The 1930's solid wall detached house (see HOBBS report) has undergone significant improvements to reduce energy use, and has achieved an air tightness figure of 7.44 m3/hr/m2 at 50 Pascals.

This is a respectable figure, given that the average new build must now achieve less than 10 m3/hr/m2 at 50 Pascals and most 1930's houses would be far more leaky than that! However, the owners have made a note of the locations where the test revealed draughts, and will be addressing those to improve the air tightness further.

The other case study to undergo an air tightness test last week was the 1950's solid wall detached house. This house is being refurbished to become an ultra-low energy home (to passivhaus refurbishment standard). It will receive a number of air tightness tests during the works, this being the first (preliminary) test with a result of 4.4 m3/hr/m2 at 50 Pascals

Following this test, the real air tightness work begins, including plastering of the walls and installation of air tightness tapes and membranes around windows, in the attic etc. This internal layer of air tightness will be the key factor in determining the eventual air tightness of this particular house. For this Passive House refurbishment, a figure of less than  1 m3/hr/m2 at 50 Pascal is required (quite a challenge!)

It should be said - while the fabric of this 1950's house is being made extremely air tight, this does not mean that there won't be good ventilation. A ventilation system (Mechanical Ventilation with Heat Recovery, or MVHR) will be installed to deliver a constant supply of fresh air to the house, and extract stale air from kitchen and bathrooms continuously. Heat from the stale air will be transferred to the incoming fresh air via a highly efficient heat recovery unit. This kind of system becomes energy efficient in houses with an air tightness of ~3 m3/hr/m2 at 50 Pascals or lower.

Tuesday, July 17, 2012

Energy Workshops and useful info from NEP

If you are thinking of doing some DIY this summer, and maybe making a few energy efficiency improvements ready for next winter, Nottingham Energy Partnership (NEP) are offering free Energy WorkshopsThese workshops are on offer to any groups and organisations who may be interested. 

NEP are particularly keen to help vulnerable groups such as the elderly, families who are less well-off, and people with health issues. So if you belong to or work with these kinds of groups, or if you can spread the word to those who may be interested, please do! 

Also, click to read the first edition of NEP's Greener Living news, their newsletter for community groups. This is usually sent out to their Energy Champions within the community groups that they work with. It includes the latest updates on help available with saving energy at home, so do make the most of it!