Energist - Part L Compliance Experts - Blog

Over the coming weeks we’ll be examining the upcoming changes to SAP and SBEM in more detail, which will hopefully give you a bit of a head start when these tougher regulations kick in come October 1^st.

This week we’re travelling north of the border, and looking at the changes which are going to be imposed on Scotland when the new Section 6 goes live – this will also be on October 1^st in line with the new SAP methodology and the new Part L.

The biggest change to Section 6 is the Target Emission Rate which is being tightened. Overall, the emission rate is being lowered by 25%, but this percentage will vary depending on the type of dwelling being built (so some houses will need a 30% reduction compared to current figures, some will only need 20%, but the national average will be 25%). This is known as the ‘Aggregate Method’ for calculating the Target Emission Rate and is being used by the new SBEM method in England and Wales.

Air Leakage Testing is another big change – but this isn’t coming into play just yet. Air tests are now commonplace at new developments in England and Wales; they are currently voluntary in Scotland. From May 2011, air tests will become compulsory for small dwellings, followed by all dwellings in October 2011 – around 5% of new houses will need to be tested.

Limiting U-Values are being reduced – walls will need to achieve an average U-Value of 0.25, ground floors will need to be 0.2, roofs 0.18 and glazing / rooflights 1.8 – these figures are lower than what is required in England and Wales.

To make things slightly more confusing, U-Values are different if you are planning a conversions project to create a new dwelling – the most noticeable change is a maximum U-Value of 1.6 for all windows, rooflights and external doors. Extension projects will fall under a third band of U-Values!

Thermal bridges are going to affect Scottish SAP Calculations more than ever before, assessors will need to look more closely at areas of a building where insulation overlaps. The Accredited Construction Scheme from the Energy Savings Trust gives more information about what building practices are required in order to comply with this section.

The minimum efficiency of heating systems is being increased – boilers running on mains gas, oil and LPG must be A-Rated for all new developments – oil combi’s can be B-Rated.

When it comes to lighting, three quarters of all internal light bulbs must be low-energy, and 100% in communal areas, such as stairwells of flats.

As this list of highlights shows, the new Section 6 is going through some substantial changes in a bid to reduce carbon emissions in Scotland. To find out how Energist can help you with future developments, call our Customer Service team on 08458 386 387.

Over the coming weeks we’ll be examining the upcoming changes to SAP and SBEM in more detail, which will hopefully give you a bit of a head start when these tougher regulations kick in come October 1^st.

This week we are focusing on air testing – an area which we’ve already featured on this blog, so here’s recap:

For the last five years in England and Wales it has been advisable to have a test completed on a newly constructed building to measure how air tight it is. This is a feature of Part L and can make a large improvement to a SAP or SBEM calculation if a good air test is recorded.

The test itself has many names… ‘Air Leakage Tests’, ‘Air Permeability Assessments’, ‘Air Tightness Testing’… whatever you want to call it, it’s a measure of how much air is escaping or entering the building through the building fabric.

The air test itself isn’t changing with the new regulations, but there are some important areas you need to bear in mind.

Firstly, the amount of air tests which are required is being increased. Officially, around a quarter of all new dwellings need to be tested when built. Any development which is registered after the October 2010 date will need to comply with the new Part L, which means around half of new dwellings should be tested. It’s fair to say that, in reality, this figure will be lower and Building Control departments will retain their discretion on which plots and how many are tested.

Commercial developments remain the same. Any building with a floor area larger than 500 sqm must be tested – anything smaller can be tested in order to achieve a lower EPC rating, but this isn’t compulsory.

The other big change is the ‘confidence factor’. Currently, if a new dwelling isn’t tested, the SAP assessment is based on the value which a builder claims they can achieve. So if a builder has achieved an air test of 6 on a previous house, the SAP for the new house can also use the same figure.

From October, if any plots are not tested, the SAP calculation must be based on the average air test value on the site, plus two. So, if you have five new houses, have two tested, one result is 9.5 and the other result is 7.6, the three other plots will be assumed to have an air leakage figure = (9.5+7.6)/2 +2 = 10.55… the highest figure allowed is 10 which means your remaining plots will no longer comply with Part L.

A good rule to remember is that individual plots must achieve an air leakage rate better than 10, the site average must be better than 8.

And just to get some scope on this, Germany has a figure around 5, Scandinavian countries are around 3 and the Passivhaus standard would expect to reach around 0.5. Air tests are being phased into Scotland next year.

For more information on this, or to arrange for an air test, contact Energist UK for a free quote on 08458 386 387.

On this blog before we have covered the news that Part L is changing, that SAP and SBEM are changing with it, and that the energy efficiency of new buildings is going to be tightened up come October.

This is happening across the UK – but how much of a difference depends on where you live and what you’re building.

Let’s start with the residential market in England and Wales. Come October there’s going to be tighter U-Values limits, new U-Values which haven’t been needed before, tighter air leakage demands, more low energy lighting, better glazing specification, fewer exemptions, more attention paid to thermal bridges and thermal mass and, the big change: a 25% reduction on the Target Emission Rate.

Compare that to what’s going to be happening in the commercial sector in Part L2 for England and Wales. For SBEM calculations, most of the regulations are staying the same as before. U-Value requirements aren’t changing, heating efficiencies are staying the same… the only difference is the 25% reduction in the Target Emission Rate… but even that’s not going to be simple.

The 25% cut is going to be an average, based on the type of building being assessed – so some commercial developers will only need to reduce their emissions by 20%, others by 30%. It’s been known for some time that particular commercial buildings fair better in the SBEM calculation than others, this system is an attempt to iron out this problem, while reducing the limits on emissions at the same time.

Confused yet… let’s head over the border.

For residential developments under Section 6 in Scotland, the Target Emission Rate is going to be reduced ‘by approximately 30%’ compared to where it is now. ‘Approximately’ is how the Scottish Building Standards Agency has phrased it – they’re using the average approach (more commonly known as the aggregate TER) which is being used on commercial buildings in England and Wales. On top of this, the SBSA is also going to be offering guidance for improving the energy efficiency of existing buildings, encouraging a greater use of low carbon systems in new homes, lowering the maximum U-Values and from 2011 air leakage testing will be brought in for the first time.

Finally for now, Scottish commercial developments. Maximum U-Values are being lowered, and are going to be different to that used on the domestic side. The Target Emission Rate is going to see a flat 30% reduction (not based on an average system) and air leakage tests will be introduced in 2011. For commercial shells, the air test must meet seven with a secondary air test to be completed once the fit out stage has been completed.

Somehow, the technical team at Energist UK understand all the changes that are being introduced into Part L and Section 6 over the coming twelve months, and will be able to help you with any queries you have. Call us on 08458 386 387.

It’s the document you’ve all been waiting for!

The 2010 Part L legislation has now been released. The books, which will not come into force until October, cover the ‘conservation of fuel and power’ in England and Wales building regulations.

The Government has released this a few months early so the building industry can get itself prepared for the oncoming changes, which will affect SAP and SBEM calculations, Energy Performance Certificates, Air Leakage Testing and the construction of new buildings and extensions alike.

Previously on this blog, we’ve already talked about some of the changes to the SAP calculator, this is a different document which will again come into force in October. The SAP methodology and Part L go hand-in-hand.

The biggest change we will notice, as expected, is that the way the Target Emission Rate is calculated is being changed… there are going to be two different methods. For SAP calculations, the TER will be calculated in the same way, but with a 25% reduction on the current regulations. This will mean new houses will need to be built more efficiently to comply.

For commercial buildings, the TER is going to be worked out in a different way to more accurately reflect the building it is being measured against. This should help to eradicate the ‘issue’ currently with SBEM that allows buildings to fly-through when air conditioning is used… A 25% reduction is also being added.

Maximum U-Values are also changing, but only on SAP. From October, all external walls must be 0.30 or lower, all roofs must be 0.2 or lower and glazing must be 2.0 or lower. In addition to this, party walls are going to be introduced into the calculations for the first time. Party walls must achieve a U-Value of 0.2 or lower.

This doesn’t apply to commercial buildings, which will use the same U-Value limits as before. Bearing in mind the lower emission target, we’re expecting developers will need to build elements far lower than these maximum values in order to comply. Maximum U-Values are also being lowered for domestic extensions.

The frequency of Air Leakage Tests is being increased, and a ‘confidence factor’ is being introduced – this is quite a positive term, when you realize it’s a way of penalising plots which are not tested.

For example, if you have ten identical plots and four are tested. The other six will need to use the average result plus two. So, remembering the air leakage limit is ten, if your average air test figure is higher than eight, any plots which are not tested will record a value higher than ten, which will not comply.

The procedure of Part L is also being tightened up – when a building is completed, you’ll have just FIVE DAYS to present the As Built reports and Energy Performance Certificate to Building Control. Also, design SAP and SBEM reports will need to be submitted to Building Control before the development is given the go-ahead by the authority.

I don’t want to re-write all hundred-or-so pages of Part L, but there are plenty of other changes being brought into effect regarding Part G, lighting and thermal bridging to name but a few.

If you would like more information on how the changes to Part L are going to effect your business, and how we can help, contact Energist UK on 08458 386 387.

For the last five years in England and Wales (and Scotland to some extent) it has been advisable to have a test completed on a newly constructed building to measure how air tight it is.

This is a feature of Part L and can make a large improvement to a SAP or SBEM calculation if a good air test is recorded. Despite this, there are still many in the industry who are new to this process, so here’s the Energist guide to an air test:

The test itself has many names… ‘Air Leakage Tests’, ‘Air Permeability Assessments’, ‘Air Tightness or Pressure Testing’… whatever you want to call it, it’s a measure of how much air is escaping or entering the building through the building fabric. (This is known as ‘infiltration’ and does not take into account elements which are purposefully designed for air flow, such as trickle vents on windows, extraction fans, flues or chimneys.

It’s important to schedule your air test at the right time – if building work is still going on, there could be air leaks which haven’t been rectified yet – too late in the build and tenants will be waiting to move in. We recommend the test is completed just before the carpets go down.

The test is completed by a man (or woman) with a van… and a fan. The first step is to temporarily seal up the ventilation elements in the building (this includes closing up the trickle vents, sealing chimneys)… this may seem to be defeating the point, but remember these air holes are already taken into account in the Part L calculation… infiltration is different to purposeful ventilation.

A fan is then attached and sealed to the front door – the building is then either pressurised or de-pressurised depending on the type of test. The fan is connected to a little box of technology which can gauge how much air is leaking out of the building – this will produce the air permeability figure, which is defined as the ‘average volume of air in cubic metres per hour that passes through one unit area of the building envelope in square metres’… (Abbreviated to m³/hm²) Don’t worry; you’re not going to be tested on that one!

The result is usually between 0 and 10 where 0 is virtually air tight and 10 is the current maximum allowed under Part L. A typical new house in the UK would be looking at around the 5-7 mark… this is quite high compared to some European countries, where the maximum limit allowed can be as low as three!

This result is then entered into your SAP or SBEM calculation before the Energy Performance Certificate is produced.

Contact Energist UK on 08458 386 387 for a free leaflet on achieving a good air test, and to book one of our skilled air testers – we operate throughout the UK.