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 going to look at heating, cooling and ventilation systems, and how your SAP calculation can be dramatically affected by the heating system you choose for your dwelling.

We’ve already covered fuel emission factors in a previous posting (which explains why different fuel types have such an impact on emission rates) so feel free to look back and catch up with us on that section!

As assessors, when we are completing a SAP (or SBEM for that matter), we have a list of dropdown boxes and options which we use to most accurately reflect the heating system to be used in a building.

This is fine for a standard house with a standard boiler, but when you get into the realms of a twelve bedroom mansion with a heat pump, separate boiler and immersion back-up, the SAP methodology doesn’t take account of the full picture.

SAP2005 can only deal with one main heating system per plot, one type of water heating and one type of secondary heating (which is either a fireplace, log burner or decorative fireplace. We can only enter one type of ventilation system (either standard extraction fans or a mechanical ventilation system) and there is no scope for entering comfort cooling systems. Also, currently heat pump efficiencies cannot be entered – SAP will always assume default figures which are usually higher than the actual product.

When the new Part L kicks in, SAP is being enhanced to give us (the assessors) a bigger array of options for the calculation… which will help to give more accurate figures overall.

The new SAP will allow two separate heating systems to be entered for one dwelling… if a heat pump is involved, we will be able to enter the actual efficiency (the co-efficient of performance) instead of having to make do with the default figure. Also, there will be the ability to enter two types of ventilation system – this will benefit large buildings which have heat recovery in some areas only.

Another change will be the introduction of cooling systems into SAP. If you are planning on installing a cooling system, your energy use will go up (which makes sense… the current SAP ignores them completely), but there’s a bit of a twist….

The assumed use of the cooling system will be geographically specific – in other words, SAP will predict the cooler will need more power in Cornwall compared to the Isle of Skye because of the change in climate. So the further south you go, the worse emission rates you’ll get. Interestingly the same does NOT apply to heating systems, although there are rumours this will be included in the next revision of SAP methodology.

If you’d like any more information on the changes to the Part L Building Regulations please give Energist on 08458 386 387 to see how we can help.

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 going to tackle thermal bridging and thermal mass – but first we need to understand what these terms mean.

Thermal bridging occurs wherever there is a break, gap or join in the insulation of a building. So that can occur where a wall and a roof meet, at corners, around window sills and door frames and between joists. Some thermal bridges are taken into account when the U-Value is calculated (such as where timber frame cuts through the insulation), but the bits known as ‘non-repeating thermal bridges’ have to be measured differently.

Why do they have to be measured – SAP measures the heating demand of a house. The more heat that can escape from a house, the harder the heating system will need to work, so SAP includes ventilation rates (to measure purposeful air holes), U-Values (to measure thermal efficiency of the envelope) and thermal bridging values (to measure the thermal efficiency of junctions in the construction.

As assessors, we currently have default figures to use - if you build to Accredited Construction Details or a similarly approved scheme, we can use one default value. If you don’t build to a recognised quality mark, we use a worse default value. The ‘value’ in question in like a U-Value, but is measured in a linear way, not area. It is called a psi-value, the lower the better.

Under the new SAP which fires up in October, the thermal bridging will need to be measured, rather than a default figure assumed. So, providing you build to a recognised scheme, we can calculate the perimeters, corner lengths and junctions of your dwelling, and provide a far more accurate result for the SAP Calculation. A worst case default figure will still be available.

So what can you do to make this figure as favourable as possible. There’s a couple of things… you can design dwellings with fewer junctions… you don’t need to go down the route of lighthouse buildings (as they don’t have corners), but less complex shapes and designs will help. Another way of lowering your psi-value is to get hold of the psi-value for individual insulation materials (this can be near impossible to find, but we expect the industry will start publishing this information once they realize this could earn them a few extra sales.

Another area of SAP which is moving away from defaults into accurate measuring is the ‘Thermal Mass Parameter’ or ‘How well a building stores heat during the day and releases into the home at night’. When compared to masonry builds, timber houses heat up quickly but don’t store heat for as long, so you use less heat during the day, but potentially more at night.

Currently SAP does not allow you to work out your own Thermal Mass Calculation, but this too is being altered. From the test studies we have completed, timber frame houses will fair better from this change to the methodology if built with a standard specification… if you are building a house with extremely low U-Values and ventilation rates, the masonry construction will fair better.

I hope that hasn’t confused you too much – out of all the changes to SAP, this is the toughest one to explain, I’m glad we’ve got that out of the way!

If you’d like any more information on the changes to the Part L Building Regulations please give Energist a call on 08458 386 387 to see how we can help.

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 lighting – there’s some important changes regarding high efficiency lighting for new residential developments, and we don’t want to keep you in the dark about them (comedic symbol crash). This change does not affect commercial developments.

Under the current SAP guidance in England and Wales, any new building must have either:

-          25% of the total light fittings must be low-energy exclusive

-          OR – there must be one low-energy light fitting for every 25m2 of useful floor space – whichever figure is greater.

A couple of things to clear up – by a ‘low energy fitting’, we are referring to a light socket which will only accept fluorescent bulbs or energy-saving bulbs… standard bayonet or screw fittings do not count. Low energy is defined as anything better than 40 lumens per watt. Energy savers are around the 60-80 mark, standard tungsten and halogen bulbs are between 15 and 25.

Also, we are talking about low wattage bulbs – these are not the same as low voltage bulbs (such as halogen downlighters) which have a similar efficiency to a typical tungsten bulb.

Lighting is treated in a strange way by SAP… if you fit your house with 100% low energy fittings, you’ll get a better EPC rating, but your Design Emission Rate will stay the same. This is because the SAP methodology is currently fixed on a 30% assumption. The EPC calculation greater reflects the reality.

So, that’s where we are now… this is where we’re going under the new SAP method…

The amount of low energy lighting is increasing to 75% - so three quarters of light fittings in new buildings will need to be low energy. But this doesn’t mean you’ll need to buy expensive low-energy fittings… you’ll be able to use standard bayonet fittings throughout the house, as long as you fit 75% of them with energy saving light bulbs.

With the phasing out of traditional tungsten lamps, it’s less likely that people are going to replace energy savers with the old fashioned lights, so the idea of having ‘dedicated’ fittings is being removed.

Also, the more energy efficient bulbs you use, the better your Design Emission Rate will be and the better EPC rating you will get – the current 30% assumption in SAP is being removed.

One final note – the definition of ‘energy efficient lighting’ is being changed from 40 lumens per watt to 45… but as long as you fit the house out with A-Rated lights (as all compact fluorescents are) then you won’t have a problem here.

If you’d like any more information on the changes to the Part L Building Regulations please give us a call on 08458 386387 to see how we can help.

As regular Energist blog readers will be aware, we’re currently bringing you weekly updates on the changes to Part L, which will effect SAP and SBEM calculations.

These changes are coming into play in October… or are they?

It was recently announced in Building Magazine that the Home Builders Federation (HBF) had written to Andrew Stunnell, the Building Regulations Minister, requesting that the introduction of the new Part L be delayed by 6 months to allow the industry more time to adapt to the changes.

To make sure you are fully up to date with all the facts, we have queried this information with one of our accreditation bodies, NHER. We currently expect Part L 2010 to be introduced – as planned – on the 1^st October 2010, as the Communities and Local Government (CLG) has not indicated otherwise. Our assessment software to be completed and approved before this date, which means any projects being handled by the Energist assessment team will be dealt with without disturbance or delay.

As there has been no announcement from CLG regarding this article, we will continue to hold Part L 2010 training seminars and provide guidance on how to pass the new SAP and SBEM regulations on the basis that the Part L changes will come into force on October 1^st.

If any official statements are made, we will of course issue an update here, on our site and inform all of out clients. Regardless, we believe it’s best to prepare for this deadline and find the date has been moved, rather than leaving ourselves and our customers caught short without the information and knowledge needed to comply.

If you’d like any more information on the changes to the Part L Building Regulations please give us a call on 08458 386 387 to see how we can help.

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.