The Code for Sustainable Homes

The Code for Sustainable Homes (CSH) has 6 levels.  Each level is an increasing reduction of carbon emissions, for example, Level 1 requires a 10% reduction of the Target Emission Rate (TER), Level 3 requires a 25% reduction, and Level 6 requires a 100% reduction and is deemed a ‘zero carbon’ structure.

Need to get planning permission first?
Under the new CSH rules, your local Planning Officer has likely requested your planning application complies with one of the 6 Levels mentioned above. In fact many Local Authorities have bypassed Levels 1 and 2 and have a minimum requirement of Level 3 on all Applications. To submit your planning application, you will need to either
a) supply a ‘Pre-Assessmnet CSH’
b) or, a full CSH to the required Level (1-6)
Your Plannning Officer will be able to inform which option is best.

Code for Sustainable Homes

What is a Pre-Assessment? 
It involves 3 main stages:
Stage 1: SAP Calculation.
Stage 2: Upgrading the SAP to include the necessary reduction in carbon emissions (Level 1–6).
Stage 3: Providing an Upgrade Report which outlines how closely the existing design is to achieving the required Code Level (set by the Local Authority Planning Dept) and any additional features recommended to meet the required Code Level (level 1 – 6). 

Need to achieve a specific Code Level?
It is anticipated that most Planning Applications will require a full CSH Assessment at planning submission stage.
Achieving Levels 1 – 6 involves a two-step process;
1) Design Stage Assessment
2) Post Construction Stage

What happens next?
If your Planning Officer requires a Pre-Assessment, the first stage is to complete a SAP Calculation and Upgrade Report on each of the dwellings.  Alternatively, if a full CSH Assessment is required, an on-site meeting (Design Stage Assessment) will need to take place.  Please advise us which option you prefer. Our Pricing Team will be able to make these arrangements and provide you with a Quotation. 

What is the difference between Ecohomes and CSH?
One of the key differences is that Ecohomes is based on the overall rating for the site built up from various elements, including location, ecology and amenities. Whereas, CSH assesses the sustainability of individual dwelling types against the specific design categories. This environmental assessment method is based on Ecohomes and many Housebuilders who currently use Ecohomes will be familiar with the credit system used within CSH. 

CSH introduces new mandartory levels of carbon emission reduction, arranged as 6 levels 

  • Level 1 = 10%
  • Level 2 = 18%
  • Level 3 = 25%
  • Level 4 = 44%
  • Level 5 = 100% / Carbon neutral
  • Level 6 = 100% + ancilliary equipment/plug-ins

Also included are new areas of sustainability design and categories such as Water efficiency, Energy efficiency, surface water management, waste management, pollution, ecology, health and wellbeing.

The specific dwellings will be selected by the Building Control Officer or Accredited Inspector.

New dwellings:
The new Part L1A Regulations came into effect on
7 April 2006 and concentrates on the Conservation of Fuel and Power within New Dwellings.

What does air tightness testing involve?
An Air Leakage Test / air tightness test will demonstrate to the Building Control Officer or Accredited Inspector that each of the dwelling designs comply with Part L Regulations.
It is beneficial to the main building Contractor for the Air Tightness Test to be carried out as early as possible, so that lessons can be learned and adjustments to design and/or site procedures made before the majority of the dwellings are built.

This information is meant as a guide to achieving a ‘pass’ result for an air leakage test / air tightness test on a residential or commercial building. The advice is based on extensive construction experience and a true understanding of air leakage testing / air tightness testing. All examples given have occurred within buildings during test conditions.

Whilst the following details are comprehensive it is impossible to identify every possibility of air leakage as each development offers a different possibility due to its design. That said, there is enough information contained here to apply to any development to achieve a ‘pass’ result.

New dwellings will require, with few exceptions, an Air Leakage Test / air tightness test to a standard of 10 m³ /h/m² at 50 Pa.

Residential Buildings - advice on types of construction

With all floor types it is important to seal service penetration points, e.g. soil pipes.
Solid and block and beam screen. This can achieve a good air barrier, but attention must be paid to any service penetration and perimeter damp proof membrane.Timber T+G on joists. Ensure joints are tight and all edges are sealed to prevent air flow.
Recommendation : tightly seal all penetration points with silicon, caulk, expanding foam or polysterene sausage-shape trim.
Flooring Panels on joists
As above

Block or brick with scratch coat, second skin, and skim
Caution: Air leakage occurs at penetration points when not well sealed.

‘Dot and dab’ plasterboard on block / brick
Caution: (i) Block work allows air to penetrate and because the dot and dab holds the plasterboard away from the surface it can thereby create a chimney effect into floors above and below. For this reason it is very important to ensure all penetration points are well sealed. (ii) At the top edge of the plasterboard, it is easy for air to flow into floor voids.
Recommendation: seal along the underside of the skirting board to create an air barrier. Seal the perimeter and all penetration points.

Timber framed / partition with plasterboard
Plaster board has excellent air tightness qualities even when taped and jointed.
Caution: Air leakage occurs at penetration points, for example, sockets, radiator pipes, light fittings, thermostats, and at perimeters, such as, behind skirting boards.

Metal ‘c’ stud with plasterboard
Caution: ‘C’ stud channels have a number of holes precut for ease of use, but these can also cause air leakage. So it’s very important to ensure penetration points are well sealed.

Taped and jointed / skimmed / acoustic
Air leakage occurs at penetration points such as spot lights, ceiling roses, extractors.

Suspended ceilings
Suspended ceilings are not designed to create an air tight barrier, so care should be taken to ensure that the ceiling above is airtight, i.e. plasterboard and perimeter sealed.

Windows and doors
Ensure the finished internal surface that meets the frame is well sealed and windows cills and thresholds are tight fitted and sealed. Door seals must be fitted.

Trickle vents
These must be fitted, and although these naturally leak air, it’s not to the extent they cause a problem.

Pay attention to the area where the flu exits.
Ensure that behind the rubber collar is sealed. Incoming pipes need to be well sealed.

Rigid pipes to radiators are easy to see and easy to seal. Flexi pipes which emerge behind the radiator are not so easy to see and can often be overlooked.

Ventilation/extractor systems
These often use a concerteena flexi pipe from a face plate to an appliance. Care should be taken to ensure that the hole cut for the flexi pipe or appliance is a tight fit and well sealed. This is often overlooked in cooker hoods with a flu cover as it is impossible to see the hole once the false flu is fitted.

Air conditioning
Air conditioning is inefficient in an environment that is not well sealed. Please ensure your AC Contractor can demonstrate the entire system including vents and extracts, is air tight.

Switches, sockets and light fittings including spot lights
When used in conjunction with plasterboard, it is important that these items are a tight fit. You may choose to seal conduits and backing boxes to create an air tight barrier.

Loft hatches
Perimeter sealed air tight ‘sit in the frame’ hatches perform best. Plastic ‘drop down’ versions need to be well fitted and the foam seal fixed.

Sun pipes
The system should be installed tightly and well sealed and ensure that the internal lense is a tight fit.

Special areas of attention

Kitchens have many service penetrations, such as outside tap, soil pipe, gas pipe. These need to be well sealed. Care should be also be taken sealing behind kitchen units at floor level as it is unlikely skirting will be fitted. This is especially important if the kitchen walls are dot and dab construction. Care should be taken if a soil stack is in the kitchen below the work surface, as it is unlikely to be sealed and this will create a chimney effect between floors and possible loft area.

Bath panels must be a tight fit, as it is unlikely skirting boards will have been fitted behind the bath. Also, as access to the pipework for the bath is often required, the bath panel tends not to be siliconed around the edges. Shower tray fronts may be treated the same as bath panels.

Toilet soil pipes often run into a boxed area that contains the soil stack. Great care should be taken to ensure that this boxed area is tight fitting and well sealed to prevent air leakage between floors or even loft spaces. Unit style bathroom units are similar to kitchen units and so should be treated the same by sealing behind them prior to fitting.

What needs to be done prior to the Air Test Engineers arrival?
The property needs to be at ‘final fit’ stage. This includes decoration, but preferably prior to the flooring/carpets being laid.

What you need to know for your ‘Guaranteed Pass’ air test:
The ‘must haves’:
We have a 100% success rate, relevant to the preparedness of the property. The areas mentioned below are absolutely necessary to achieving a ‘pass’ result;

1. Each of the 6 surfaces of each room (walls, ceilings, floor)
must provide an air tight barrier.

2. The property must be at ‘final fit’ stage and decorated.

3. A skilled site worker needs to be on site at the time of the
air test so that any remedial work can be done straight away
if the initial air Test achieved a borderline ‘fail’ result.

For full details refer to our website or contact our Customer Support Team.

Our ‘Fast-track’ service
If you have an urgent situation, Air pressure Testings  UK-wide team of Test Engineers will be there to help, We can undertake a last minute air test, out of hours  Please contact Air Pressure Testing Ltd now if you need to pass your Air Leakage/ Air Tightness Test within a few days to attain practical completion

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