YOUR COMPLETE GUIDE TO

PART L 2014All you need to know about energy efficiency

regulations in Wales from July 2014

The Team that de-risks the Regs

ContentsYour free guide from Energist UK

2

3 Welcome message From Sarah Fenwick

4 Regulation changes What’s new?

5 Bridging the gaps SAP is focused on heat loss

from thermal bridges

6 Limiting U-Values Design flexibility over tougher insulation requirements

9 Keeping hot water hot More insulation required for pipework

10 Part L1B Using Part L with extensions and renovations

12 Emission factors Carbon intensive fuels

13 Turning down the heat Quite literally in the background of SAP!

14 Elemental recipes - Wales How to comply with the new targets

16 Feasibility checking High Efficiency Alternative Systems

18 Off grid developments How the targets change for homes without gas

19 Part L2A Changes for non-domestic new builds

22 Part L2B Non-domestic refurbishments

23 Looking ahead What’s next for our industry?

24 The end of CSH and BREEAM National Development Management Policy binned

26 What has happened in England?

27 What will happen in Scotland?

Handy poster included for the PartL1A and 2A recipes

t: 08458 386 387

e: info@energistuk.co.uk

@EnergistUK

Maximum U-Values for

commercial buildings,

renovations and

extensions.

These are:

NEW BUILD:

Floor 0.25

Wall 0.35

Roof 0.25

Openings 2.20

REFURB:

Floor 0.25

Wall (Retro-filling

empty cavity) 0.55

Wall (all other cases) 0.30

Roof (insulation in ceiling) 0.16

Roof (all other cases) 0.18

EXTENSIONS

“DOMESTIC IN

CHARACTER”:

Floor 0.18

Wall 0.21

Roof 0.15

Glazing: 1.60

EXTENSIONS - ALL

OTHER CASES:

Floor 0.22

Wall 0.26

Roof (insultion in ceiling) 0.16

Roof (all other cases) 0.18

Glazing: 1.80

BPEC / TPEC:

The Target Primary Energy

Consumption applies to all new

commercial buildings in

Wales, as well as the Target

Emission Rate.

U-VA LUES

S U M M A RY

Part L2A 2014 Summary

There isn’t a one-size-fits-all answer for constructing a

compliant commercial building to Part L 2014 standards,

but this elemental recipe is certainly a good place to

start. An SBEM is a great way of experimenting with

different ingredients to find your preferred method.

FEEDS: Anyone - from the smallest corner shop

to the largest of factories

INGREDIENTS:

For the casing:

0.22 U-Values of floor

0.26 U-Values of wall

0.18 U-Values of roof

1.50 U-Value for vehicle access doors

2.20 U-Value for other external doors 

Windows should have a U-Value of 1.6 with 10% framed area

The G-Value is 40% and light transmittance is 71%

Rooflights should have a U-Value of 1.8 with 15% framed area

The G-Value is 55% and light transmittance is 60%

For the filling:

You can fill your building with a myriad of heating systems

- this recipe assumes you’re using a gas boiler.

Use a 91% efficient mains gas boiler to provide all heating

and hot water.

Use a lighting system throughout the building with an

efficiency no lower than 65 lumens per circuit watt

Lighting should be made more efficient by using occupancy

controls and daylight controls

The Recipe for Air

Test Targets:

Buildings with

rooflights only

for natural light:

All other cases:

Building area <250m27

5

Building <3,500m27

3

Building <10,000m25

3

Building >10,000m23

3

Ventilation:

Based on 70% efficient heat recovery ventilation system with

central specific fan power of 1.8 w/l/s and terminal unit of 0.3 w/l/s

Cooling:

Where a building has cooling, the recipe operates at a SEER

efficiency of 4.5 if part of an air conditioned, or 2.7 if mixed mode.

Renewables:

PV panels - array size of 5.3% of the total floor area.

CHEF’S TIP:

If the building is not on the

mains gas grid, or you’re

using a different type of

heating system, the Elemental

Recipe will change to more

accurately reflect your actual

heating system.

Start with the casing... Construct the shell using your floor,

wall and roof materials. A roof of 0.18 can be achieved

with 250mm mineral wool. A cavity wall of 0.26 can be met

with a fully filled 300mm wall with thermal blocks. If you

are using prefabricated materials, it should be quite

straightforward to surpass these values, and improve

your recipe.

Openings... Solar gains from south facing windows are a

good way of reducing heating demand for your building, but

if you’re planning on using a cooling system, too much south

facing glass will increase cooling use, and increase the

overall emissions

CHEF’S TIP:

You can vary the recipe to taste, but you

need to keep the ingredients balanced.

For example, you can use a natural ventilation

system instead of heat recovery, but

you’ll need to compensate for this – maybe

by using a higher efficiency lighting system.

As a general rule, the building fabric

doesn’t have as much of an impact

as the building

services.

YOUR RECIPE FOR COMPLIANCE

WALES

CHEF’S TIP:

Depending on your building use,

services will be assessed differently

in SBEM. For example, a building which

uses a lot of hot water – such as a sports

hall with a large shower block – would

benefit from solar water heating...

but this type of system would

be next to useless on a building

such as a warehouse, where the

hot water demand is zero.

Install your preferred heating, hot water, ventilation and

lighting systems. Remember to look at improving on the

details in the recipe wherever possible.

Did you notice there are renewable technologies in the recipe?

If you were to install more on your building, you’ll show an

improvement over the recipe. It will be extremely difficult to

meet the recipe without renewables.

Next, arrange for your air test to be completed on the

building. Remember the recipe target changes depending on

the building size, and the type of building.

Store your SBEM and EPCs in a safe place for future reference.

Your commercial building is ready for use. Serve immediately.

Part L1A 2014 Summary

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We know there are hundreds

of great ways of building the

perfect house. This recipe is

a sure-fire way of passing the

Part L taste test every time!

FEEDS:

For the whole family

INGREDIENTS:

For the casing:

0.13 U Values of floor

0.13 U Values of roof

0.18 U Values of walls*

1.40 U-Value for windows

and rooflights,

1.20 for semi-glazed doors

and 1.0 for solid doors**

Thermal Bridging - Y Value of 0.05

*Aim for no heat loss through party walls

**Glazing = 25% of total floor area

For the filling:

89.5% mains gas boiler with zone control

(where feasible) and weather compensator.

Hot water cylinder (if being fitted) to have

heat loss no worse than 1.39 kWh daily.

100% low-energy lighting

5.0 predicted air test

Extraction fans where appropriate

WALES

YOUR RECIPE FOR COMPLIANCE

@EnergistUK

Maximum U-Values for new

dwellings, renovations

or extensions.

These are:

NEW BUILD:

Floor 0.18

Wall 0.21

Party Walls 0.20

Roof 0.15

Openings 1.60

REFURB:

Floor 0.25

Wall 0.30

Roof (insulation in ceiling) 0.16

Roof (all other cases) 0.18

EXTENSIONS:

Floor 0.18

Wall 0.21

Roof 0.15

Glazing 1.60

Other limiting values:

AIR LEAKAGE TESTS:

Results must be no higher than

10 m3/hm2 (although it’s likely

you’ll need to go lower than

this to pass the SAP)

LOW ENERGY LIGHTING:

At least three quarters of fixed

light outlets must be fitted with

low energy bulbs

HEATING:

Each type of heating

system must meet limiting

efficiencies. These include

gas and oil boilers (88%), heat

pumps (2.5 CoP), and wood

burning stoves (65%).

VENTILATION:

If Heat Recovery systems are

installed, the efficiency should

be higher than 70%.

U-VA LUES

Start with the casing… Construct the shell using your floor, wall and roof materials. A floor of 0.13

could be achieved with 150mm PU under a screed. A roof of 0.13 could include 350mm mineral wool

quilt. A 0.18 wall could be achieved using brick and block with 140mm cavity with 90mm PU Foam

Board, or by using SIPs or a timber frame construction. Don’t forget to use approved thermal bridging

details and pipe insulation to prevent unnecessary heat loss.

Include your openings… the sunnier the better! High spec double glazing can achieve 1.40, but expect to

use triple glazing if you go much lower.

Install your desired ventilation, heating and lighting systems. Remember to stick to or improve on the

recipe details for all building services.

Arrange for your air test to be completed – remember to aim for 5 or lower.

Store your SAP and EPCs in a safe place for future reference.

Your house is ready to serve immediately.

S U M M A RY

CHEF’S TIP:

You can vary the recipe to taste, but you

need to keep the ingredients balanced.

For example, you can decrease your wall

thickness and reduce insulation, but you

might need to offset this with flue gas heat

recovery. Alternatively, you could cut

back on your heating controls but you

might need to install a mechanical

ventilation system, especially if

your air permeability

is below 5.

CHEF’S TIP:

If you’re not on the gas

grid, the target will be

adjusted depending on

the fuel of your main

heating.

CHEF’S TIP:

If you’re not already, we recommend you

research and adopt some form of thermal

bridging details for all new dwellings, as this is

one of the key ingredients in the recipe.

The most common junctions are the

Accredited Construction Details, but as these

perform worse than the details used in the

Elemental Recipe, it’s worth finding out if

you can build your junctions to a higher

standard. Other details are available

online, from manufacturers, or can

be calculated for your

specific construction.

t: 08458 386 387

e: info@energistuk.co.uk

w: www.energistuk.co.uk

YOUR GUIDE TO AVOIDING FALLING FOUL OF ENERGY REGULATIONS

Sarah has personally prepared a guide to the Part L regulations, looking at how they can affect your build.

The guide discusses the common energy mistakes made during construction and how our services can save you time and money. Request your free copy of ‘Avoid Falling Foul of Energy Regulations’ today by emailing us at:info@energistuk.co.uk.

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Welcome messageFrom Sarah Fenwick, Managing Director of Energist UK

In construction, one size never fits all.

Every region has its own concerns, its own way of working and its own regulations. Energy efficiency and sustainability may be global responsibilities but the work to make change is local, so we make sure that when we work in Wales, we know what Wales needs.

But it can be hard to find reliable, easy to understand advice dedicated to Welsh construction. That’s why we put together this guide, where you’ll find everything that makes Welsh regulations different, how they’re changing and how they fit into the bigger picture.

And if you find yourself needing more help with Part L in Wales, we provide free, region specific CPD from our energy experts. Energist is always up to date and always looking forward, so feel free to get in touch if you want to make Wales better.

Regulation changes - what’s new?Lower emission rates, lower U-Values and a new balancing act

THE BUILDING REGULATIONSOf all the different Approved Documents of Building Regulations, Part L is the one which gets modified the most. The Government is pushing us towards a Zero Carbon Homes target, and the only way we’re going to get there is to keep on tightening the Target Emission Rates which lead to the construction of more energy efficient buildings.

The most recent update to Part L was in July 2014. This brought in a new Target Emission Rate which is typically 8% tougher than Part L 2010 for new dwellings in Wales, and around 20% tougher for non-domestic buildings.

This is the first version of Part L with separate legislation for Wales and England – this new version has been based on the Westminster copy, but amended by the Welsh Government in Cardiff.

It means developers who build on both sides of the border will need to be aware of the two separate regulations, and will probably need two different building specifications to meet both requirements.

If you’d like a copy of our free guide to the English Part L, get in contact at info@energistuk.co.uk.

TOUGHER, BUT SIMPLIFIEDAlthough the targets for new buildings are more difficult to hit than ever before, the way of working out the target has been simplified – see the poster included for the ‘2014 Elemental Recipe’.

A specification has been created which gives developers one way of showing compliance with the Target Emission Rate. If any parts of this ‘recipe’ are too difficult to achieve or not cost effective, there is flexibility built-in to allow for improvements and alterations elsewhere.

A similar recipe has been created for commercial buildings, with variations between Welsh and English recipes.

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5

Bridging the gapsSAP is now more focused on heat loss from thermal bridges than ever before

When Part L 2010 was launched, the need to build to Accredited Construction Details, or use similarly approved schemes, became much more of an issue.

From October 2010, builders had to show they were constructing junctions of their buildings to a particular standard to ensure that heat losses through insulation breaks were kept to a minimum.

Failure to build to these thermal bridging standards often led to the SAP assessment failing against the Target Emission Rate.

Now that builders and architects are used to the idea of building to this higher standard, a more detailed assessment has been released into the updated SAP software.

Until now, the only junctions that have been measured are those which adjoin external walls – so this includes corners, where the floor meets the wall and surrounds for windows.

Now, roof junctions are also required. This means that any break in the roof insulation will need to be entered into SAP. This includes the perimeter of flat roofs, the insulation line where there is room in the roof, and the surround of roof lights.

Thermal bridges have also been brought in for where heat loss walls meet basement floors.

If you’re not familiar with thermal bridging and which details to build to you can look up these and others, online:

Accredited Construction Details Enhanced Construction Details Constructive Details Concrete Block Association

By building to these details, you will limit heat loss from thermal bridging and improve the energy efficiency of the dwelling, bringing compliance that bit closer.

Some manufacturers of blockwork and lintels have their own psi-values, so it’s worth checking with your suppliers, as these usually perform better than the default figures used in SAP.

Alternatively, you can have your details calculated to determine the heat loss, and provided this has been done in accordance with BR497, these values can be used in the calculation.

A thermal bridge

Limiting U-ValuesTougher insulation levels lead to Fabric First design

The second biggest change to Part L 2014 (behind the tighter Target Emission Rate) is a new set of limiting U-Values for domestic buildings – they are much lower than the previous set of U-Values, and may take some getting used to.

This means that more insulation will be needed in heat loss floors, walls and roofs, and you’ll also need to look into better specifications for windows, rooflights and external doors.

But meeting these new U-Values is unlikely to be enough to show overall compliance with the SAP assessment – you’ll be expected to push even further in other areas. It’s all tied in with the term ‘Design Flexibility’.

EXPLANATIONWhen your dwelling is assessed in SAP, the Target Emission Rate is created using the dimensions of your dwelling, but based on the specification as listed on the ‘Elemental Recipe’ poster.

The idea behind Design Flexibility is that you are allowed to build any U-Value up to the figures as listed on the next page, but if you are using a worse specification than that listed in the Recipe, you would need to make up for it elsewhere.

We would recommend using the Recipe as your starting point for a specification, not the limiting U-Values as shown here.

PART L 2014 U-VALUESTo show full compliance with Part L 2014, you need to make sure you are achieving these U-Values (right) – these are known as ‘area-weighted’ which means some elements can be of a worse standard, providing the average U-Value of all floors, walls or roofs are no higher than the figures shown.

An example wall section

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This is the full set of limiting U-Values expressed in W/m2K, which you are allowed to build to under Part L 2014. These U-values apply to Wales only.

WALES PART L U-VALUES

DWELLINGSFloors Walls Roofs Glazing

L1A New Build 0.18 0.21 0.15 1.60

L1B Extension 0.18 0.21 0.15 1.60

L1B Upgrade 0.25 0.30 - 0.55 0.16 - 0.18 1.60

COMMERCIALFloors Walls Roofs Glazing

L2A New Build 0.25 0.35 0.25 2.20

L2B Extension (Domestic)

0.18 0.21 0.15 1.60

L2B Extension(Commercial)

0.22 0.26 0.15 - 0.18 1.80

L2B Upgrade 0.25 0.30 - 0.55 0.16 – 0.18 1.60

NOTES: Party walls in the domestic sector must achieve a U-Value no worse than 0.20.

Heated swimming pool basins must be insulated to achieve a U-Value of 0.25.

Under Part L1B and L2B, the maximum U-Values allowed for upgrading existing walls vary depending on the type of wall. If it is an uninsulated cavity, it should be upgraded to achieve 0.55. In all other cases, it should be upgraded to achieve 0.30.

When renovating an existing domestic roof, a U-Value of 0.16 should be achieved where insulation is laid horizontally within the loftspace. In all other cases, the U-Value needs to achieve 0.18. For commercial extensions where the building is domestic in character, a U-Value of 0.18 can be used where insulation is sloping.

Upgrade U-Values vary depending on existing construction

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Limiting U-ValuesContinued

U-Values for commercial extensions vary depending on whether the building is ‘domestic in character’ or not – See Page 21)

Limiting U-ValuesContinued

It’s all very well playing with numbers and saying more insulation is required for compliance, but what do these new limiting U-Values mean in the real world? Here are a few ideas on how to comply, remember you’ll want to aim higher than these values to ensure compliance with the Elemental Recipe.

Note that all of the following are based on standard products. You should have U-Value calculations completed based on your bespoke building specifications.

OPTIONS - NEW FLOORSA ground floor U-Value changes depending on the size and shape of a building, but typically you could expect to achieve a U-Value of 0.18 by installing 100mm polyurethane board under a concrete screed.

OPTIONS - NEW WALLSTo meet a U-Value of 0.21 with a brick and block cavity, you’d be looking at a 150mm fully filled cavity, or you could go slightly thinner with 90mm PU foam board and a suitable cavity.

If you’re into timber frames, 0.21 could be met using 175mm mineral wool (100mm in the timber frame and 75mm in a cavity, or you could use a total of 120mm PU board as an alternative insulation material.

OPTIONS - NEW ROOFSA U-Value of 0.15 should be easily achievable where insulation is laid horizontally; probably around 275mm mineral wool.

Where insulation slopes, you’ll be looking to install about 180mm PU foam board insulation, or you could reduce this insulation thickness by installing a thicker, insulated plasterboard.

Also, remember U-Values apply to any heat loss area. So this includes floors above garages, walls adjoining unheated corridors, basement walls and stud walls for rooms in roofs.

OPTIONS - GLAZINGThe average U-Value for all windows, rooflights and external doors needs to be no higher than 1.60. All of the main manufacturers now create specifications which match this as standard. It’s achievable by using a uPVC or timber framed double glazed window with low-e coating and an argon filled cavity at least 16mm wide. When asking your glazing supplier for a U-Value, make sure they provide a figure for the whole unit, and not just the glass.

For further details on how to show compliance with Part L1B, see Page 10, and for non-domestic construction, see Page 21.

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9

Keeping hot water hotMore insulation required for pipework

A new section of SAP has been brought in to measure more accurately how much energy you lose from the hot water distribution pipework.

It is now possible to assess heat loss from pipework with one of the following options:

First metre of pipework from cylinder insulated

All visible pipework insulated No insulation on the pipework at all Fully insulated

Also, hot water cylinders which don’t have separate timers and thermostats will perform worse in the SAP because it’s expected that more energy will be used (by people leaving it on for most of the day).

SHOWERSUnder 2010 regs, SAP didn’t pay any attention to the type of showers you installed in a dwelling.

This means that, until now, you could install solar thermal panels to the roof of your house to generate lots of lovely, free hot water… and then fit electric showers which take cold water from the main supply and SAP wouldn’t realise that you’re not using the solar system to its full potential.

In the new methodology, if you are installing a solar thermal system, SAP will need to know the type of shower you are fitting. If you are using an electric power shower, it will assume that your solar hot water is going to waste, and will give you a worse result.

ALTERNATIVE:As an alternative to measuring the thickness of insulation on your cylinder, the SAP assessment can take into account the specified daily heat loss figure. This information is usually stamped on the cylinder itself, or available from a manufacturer’s website.

Part L1BUsing Part L with extensions and renovations

Part L1B applies to existing dwellings that are going through substantial building changes such as extensions, conversions or a change of use. There are different requirements when compared to Part L1A (which applies to new build).

EXTENSIONS:Extensions which do not include much glazing can usually get away without a SAP calculation, providing the developer can confirm that any new elements comply with Building Regulations.

The full set of U-Values is listed on Page 7, and there are different minimum requirements depending on whether you are building a new element from scratch, or whether you are upgrading an existing element.

As we mentioned previously, limiting U-Values for domestic extensions are now lower than those required in the 2010 set of regulations.

When building an extension, you may not be required to upgrade the existing house, but obviously you can if you like! If upgrading, you must meet the limiting U-Values (although there are leniencies which means you may be allowed to build to a ‘lesser provision’ if there are issues with head height or loss of room area for example).

If you are replacing building services, such as heating, ventilation and lighting, the efficiencies and fittings of the new items must comply with the Domestic Building Services Compliance Guide.

For extensions which are heavily glazed, you are required to have a SAP assessment completed to prove that the proposed extension will perform no worse than in a ‘notional’ calculation.If the extension faces south, the SAP calculation doesn’t usually cause issues with compliance, as the improved solar gains created by the glazing makes a good saving on your heating and lighting bills. If your extension faces any other way, you may be required to improve the specification of the building fabric or heating details.

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If you believe completing such renovation work isn’t viable, SAP can be used to complete an economic viability study. If the cost of making a particular improvement is more than the anticipated saving in running costs over 15 years, then you don’t have to do it.

The same rule applies if you are looking to change building services such as boilers or lighting.

CONSEQUENTIAL IMPROVEMENTSA new section in L1B now requires developers to complete ‘Consequential Improvements’ for domestic extensions.

This means you need to make improvements to the original part of the dwelling to improve energy efficiency.

There are three rules to follow. Rule 1 applies in all cases, the others apply to extensions larger than 10sqm only:

1 If the existing house has less than 200mm mineral wool quilt in the loftspace, this should be increased to at least 250mm.

2 If the existing house has uninsulated or partially insulated cavity walls, they should be filled where suitable.

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3 If the hot water cylinder has an insulation jacket less than 100mm thick, upgrade to a thickness of 160mm or, if the hot water cylinder has factory fitted foam less than 25mm thick, add an 80mm thick insulated jacket.

FEASIBILITYThere are some get-out clauses built into Part L1B, which means a lesser provision may be allowed by Building Control if building to the Regulations or adhering to Consequential Improvements are seen not to be ‘technically, functionally or economically feasible’.

Something is not technically feasible if the required upgrade would be too difficult to implement.

Something is not fuctionally feasible if the required changes would impact the lifestyle of the occupants, for example by reducing head heights.

For something not to be economically feasible, you need to prove that the expected cost of an upgrade is more than the expected fuel bill savings over 15 years. SAP assessors can help with justification on this point.

Part L1BContinued

Emission factorsCarbon intensive fuels

The results of the SAP and EPC reports are based on what is called ‘regulated energy’. This takes into account the energy used for heating, hot water, cooling, lighting and ventilation only. The reports do not cover appliances or cooking.

The different types of fuel that we use in our homes can be translated into carbon emissions and running costs per kWh. These fuels include grid electricity, gas and oil, but also cover wood logs, LPG and even anaerobic digestion.

When we talk about ‘Emission factors’, SAP is looking not at the efficiency of fuel within your dwelling, but at the bigger picture. This covers the efficiency of how the UK produces and sources our power and how the fuel is transported across the country.

Type Emission Factor(grams of CO2 per kWh)

Unit Price(£/p per kWh)

Mains Gas 216 (Up by 18) 3.5p + £120 a year

LPG Bottles 242 (Down by 3) 9.9p

Oil 298 (Up by 24) 5.4p

Logs 19 (Up by 11) 4.2p

Electricity 519 (Up by 2) 13.2p + £54 a year

Bioethanol 140 (Up by 76) 47.0p

For example, electricity has a high emissions factor, because as a nation we are still using a lot of fossil fuel fired power stations. Wood logs have a low emission factor, because a tree absorbs CO2 during its life, releasing it again when burned.

This means that, if you are using an electric boiler, your carbon emission rate will be much higher than if you were using mains gas. This will make it harder to comply with Part L.

If you chose a bioethanol heating system, your emission rate would be much lower, but your Energy Performance Certificate (EPC) rating would be worse. This is because bioethanol costs more per kWh, and the A to G rating on the EPC is based on running costs.

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13

Turning down the heatQuite literally in the background of SAP!

SAP is now able to include more heating and hot water options than ever before. Here are some of the bigger changes:

You can now include hot water only heat pump systems. Up until now, it has only been possible to enter a heat pump which provides hot water and heating.

The efficiency of certain heating controls (such as weather compensators and programmable TRVs) is now available within the SAP methodology. This means that the actual tested efficiency of these units is reflected in the calculation. If you are installing a heating control system which has been proven to reduce energy bills, this will be reflected in your Dwelling Emission Rate.

The temperature which a heating system has been designed to operate at is now changeable in SAP. In previous versions it was always assumed a heating system would operate at 55°C or higher, but systems which run at lower temperatures are known to be more efficient. If your heating system operates at 45°C or even 35°C, this will show as a positive impact in the SAP.

If you are installing a heat pump, you will get a better SAP rating if you can provide your assessor with a MCS certificate from the installer. This is seen as proof that your system was installed by a competent tradesperson, and therefore it is assumed that the system will operate more efficiently.

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Elemental recipes - WalesHow to comply with the new targets

There is now a single building specification which sits in the background of SAP, and is used to calculate the Target Emission Rate (TER). In theory, if you follow this ‘Recipe’ word for word, you should show full compliance with the new Part L.

But is this Recipe the most sensible, economical and feasible approach for your development? Unlikely!

You can look at this Recipe as a series of weights on a scale – you can move weights from one side to the other providing you keep it balanced. In other words, you can make certain elements of the specification worse if that suits your needs, providing you make improvements to other areas of the specification.

This means that you do not have to construct to this Recipe, but it’s a good place to start.

This Recipe applies for new build dwellings in Wales where gas heating is to be used. For homes which are off the grid, a leniency factor is applied to this Recipe to take into account the different factors of different heating fuels (see Page 18 for more details).

SIZE AND SHAPE: The TER is modelled on your house, so all dimensions, heat loss areas and the building volume

will be calculated based on the actual dwelling.

HEAT LOSS FLOORS: All heat loss floors – such as basements, ground floors and upper floors above garages – are calculated with a U-Value of 0.13. For a typical detached dwelling, this could be achieved using 150-160mm PU foam board insulation below screed. The thickness of insulation required would depend on the size of the building.

HEAT LOSS WALLS: All heat loss walls – such as external walls and those adjoining unheated spaces (like communal corridors or garages) – are calculated with a U-Value of 0.18. With a cavity wall, this could be met with brick and block, using a 150mm fully filled cavity, or 90mm PU foam board insulation (total wall thickness of 340mm including clear cavity).

With a timber frame, you could use brickwork externally with a 160mm timber frame filled with high performance mineral wool batt.

Party walls should be suitably insulated and sealed to prevent heat escaping into the cavity and exiting the building through the loft space.

HEAT LOSS ROOFS: All heat loss roof spaces are calculated with a U-Value of 0.13. This can be achieved in insulated flat ceilings with 350mm mineral wool

quilt laid between and over the roof joists. For a sloping roof, 0.13 could be met with 125mm PU foam board between rafters and 80mm under. This sloping ceiling construction could limit head heights, making it impractical. You would then have to reduce the insulation in the sloping ceiling and offset this elsewhere in SAP.

OPENINGS: Based on glazing and roof lights hitting a U-Value (including frames) of 1.4. External, solid doors are set to 1.0 and 1.2 for semi-glazed doors.

The Recipe is based on the same area of openings as the real house, up to 25% of the total floor area. This means that homes with more glazing than 25% are likely to perform better if lots of windows are south facing, but may perform worse if windows face north.

THERMAL BRIDGING: The y-Value (W/mK) used in the Recipe will vary, but will typically be around 0.05 (the lower the better). To put this into context, the use of Enhanced Construction Details will achieve around 0.04, Accredited Construction Details around 0.08, and not adopting any thermal bridging best practices will give you a worst-case 0.15.

VENTILATION: Based on System 1 – up to four intermittent extraction fans. The use of System 3 or System 4 ventilation may help here.

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AIR PERMEABILITY: Based on a result of 5. You don’t want to go much lower than this with System 1 ventilation or you may conflict with the requirements of Part F.

HEATING: A mains gas boiler with a space heating efficiency of 89.5%, fitted with a weather compensator and zoned time and temperature controls (except for studio apartments where zoned controls aren’t practical). You could add delayed start thermostats or flue gas heat recovery to improve your result here.

HOT WATER: If you’re installing a water cylinder, a heat loss value is calculated based on storage volume. The cylinder should be in a heated space, have separate timer controls and all primary pipework should be insulated.

SECONDARY HEATING: None listed. If you install a wood burning stove or fireplace, this will give you a positive improvement over the Recipe. Electric fires would have a negative impact.

COMFORT COOLING: None listed. Adding comfort cooling will increase energy use and give you a worse result.

LIGHTING: All internal bulbs are to be low energy. The minimum requirement in Part L is 75%.

SOLAR: None listed. Using solar thermal or PV panels will give you an improvement over the Recipe.

Elemental recipes - WalesContinued

Feasibility checkingHigh Efficiency Alternative Systems

It is now a requirement for developers to show they have considered the feasibility of using low and zero carbon technologies on all new developments.

This report is known as the High Efficiency Alternative Systems analysis.

This has been brought in across the EU as a drive to raise awareness about technologies more than anything else – there’s nothing mandatory in this

requirement to impose renewable systems on new developments – it’s purely a feasibility exercise.

When you are putting together a Building Regulations application, you should include a brief assessment which shows the pros and cons of installing the following technologies on your site:

Wind power / turbines

Photovoltaic panels or solar thermal panels

Air source heat pumps

Ground source heat pumps

Water source heat pumps

Tidal power / Investing in wave farms

Hydropower / Waterwheels

Biomass / Log burning systems

Landfill Gas solutions

Biogases / anaerobic digestion

District Combined Heat and Power solutions

Micro Combined Heat and Power boilers

Existing District Heating systems

The idea behind this document is to show developers what is feasible, and may encourage more low and zero carbon technologies to be installed in future developments.

16

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So let’s say, for example, that you’re building a new cul-de-sac of 15 reasonably sized houses in a city suburb with all houses facing east or west. The plans show the new houses are tightly laid out between existing terraces and therefore have very small gardens.

What’s feasible in this scenario?

Some options are easy to rule out... there’s no district heating system, no oceans and no anaerobic digestion plants nearby, they can be ruled out immediately.

Ground source heat pumps wouldn’t be suitable if there isn’t enough garden space to bury coils

Wind turbines are unlikely to go through planning if there are too many houses nearby.

Others need a bit more consideration:

Solar panels might work to some extent, but without south facing roofs, they won’t perform as efficiently as possible.

Community heating could be an option, but you’d need a dedicated plant room on site, and you’d need to consider the cost of installing such a system.

Air Source Heat pumps could work, but would 15 units cause noise disruption to residents?

A small Combined Heat and Power system is unlikely to operate efficiently if the houses are well built (as lower heating demands lead to CHP working less efficiently).

Wood burning stoves could be an option, as long as the layout of the floor plans can be adjusted to incorporate flues and there are no smoke control issues.

Biomass boilers might work, but each house would need space to store fuel, and you’d need to make sure there’s a reliable supplier close by.

So it could be feasible for this development to install wood burning stoves or air source heat pumps.

Feasibility checks now apply to all new developments as part of the information you need to supply to Building Control.

Feasibility checkingContinued

Off grid developmentsHow the targets change for homes without gas

The Elemental Recipe calculates the Target Emission Rate based on mains gas heating.

If you are working on a development which does not have access to mains gas, or isn’t going to be using gas in any way, the Target Emission Rate is adjusted to take this into account.

When you consider that fuels such as electricity have a much higher emission factor than gas, it makes sense that homes with electric heating typically have higher carbon emission rates.

To make the playing field a bit fairer, a value known as a ‘Fuel Factor’ is added to the Target Emission Rate for any homes which are off grid. It’s a simple calculation... Take the elemental recipe (which is based on a mains gas heating system), and multiply the result by...

1.06 if the heating is LPG

1.17 if the heating is oil

1.55 if the heating is electricity

1.35 if the heating is solid fossil fuels

Some of these fuel factors have been adjusted slightly as part of this revision – it means the new target is going to be more lenient on houses with electric heating, but on the flip-side, the target is going to be slightly lower (so more difficult to achieve) with oil heating.

How much of a difference these adjustments will make is very difficult to predict. We’d prefer to save recommendations until we’ve assessed your dwellings and the proposed specification.

As certified CPD providers we are able to offer CPD training on all

the Part L 2014 changes in Wales. If you would like to

attend one of our events please email:

cpd@energistuk.co.uk

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Part L2AChanges for non-domestic new builds

To show compliance with Part L2A, you must be able to prove the Building Primary Energy Consumption (BPEC) is lower than the TPEC, and also that the Building Emission Rate (BER) is lower than the TER.

These changes to the Regs are likely to mean that new non-domestic buildings will need to incorporate low carbon or renewable sources in some capacity, as well as focusing heavily on Fabric First building standards and the use of high-end efficiency heating and lighting systems.

THE TER

Both targets are calculated using an ‘Elemental Recipe’ – the theory being that if you build to this Recipe, you should achieve compliance; however it’s not a one-size-fits-all approach.

The following specification lists how the TER and TPEC are calculated for the majority of commercial buildings.

You do not need to stick to these details, but for any items where you fall short of the recipe, you’ll need to make improvements elsewhere to tip the balance:

HEAT LOSS FLOORS: U-Value of 0.22. The specification will change depending on the size and shape of the building, but typically this U-Value could be achieved with 70mm PU foam board under a concrete screed.

Where you have a new building which isn’t domestic – such as an office, school, pub or sports hall, Part L2A applies, and you’ll need an SBEM assessment.

This is similar to the SAP except it goes into more detail about the expected use of a building – after all a school is going to experience very different energy requirements when compared to a warehouse or a factory.

SBEM (Simplified Building Energy Model) still takes into account U-Values for the building fabric, air permeability, as well as heating, ventilation and lighting design.

As with the domestic sector, the Target Emission Rate (TER) is being lowered – but this target is much tougher than for domestic; 20% lower than the 2010 version of Part L.

On top of this, a new secondary, mandatory target is being brought in to force for the first time: The Target Primary Energy Consumption (TPEC).

The TPEC looks at the primary energy consumption of the building only – this cover the types of fuel being used (electricity, gas etc) and how efficient the building services are.

The TER looks at the expected carbon emissions of the building. This calculation includes the efficiency of services, but also covers building fabric and air tightness.

Part L2AContinued

HEAT LOSS WALLS: U-Value of 0.26. This is achievable with a 300mm brick and block cavity using a decent fully filled insulation. It’s also easily met with pre-constructed metal cladding systems. Timber frame designs would typically perform even better again.

HEAT LOSS ROOFS: U-Value of 0.18. If your roof insulation is laid horizontally, this could be met with 200mm mineral wool quilt. Where insulation is sloping, you’d be looking at around 120mm PU foam board.

OPENINGS: The Recipe assumes all windows have a U-Value of 1.60 and 1.80 for roof lights. Both of these values are possible using modern, double glazed units with either a timber or uPVC frame. It may be more of a struggle with metal frames or curtain walling, but your manufacturer will be able to give you more details. The g (solar gain) value is also specified at 0.4 to minimise cooling demand, so it’s important this is accurately assessed.

AIR PERMEABILITY: This will be 5 for most cases, but this value will vary depending on the type of building and the size. The Recipe of the air permeability ranges from 3 to 7.

HEATING EFFICIENCY: If you’re using mains gas, the Recipe is calculated based on an efficiency of 91% to provide all of the building’s heating and hot water. Different scenarios are used for different heating systems.

VENTILATION: The Recipe uses a heat recovery ventilation system which operates at an efficiency of 70% with a central specific fan power of 1.8 W/LS and terminal SFP of 0.3. Remember you don’t need to install such a system – you could use intermittent extraction fans providing you make savings elsewhere in the Recipe.

COOLING: For commercial buildings which are fitted with cooling systems, the Recipe will assume a Seasonal Energy Efficiency Ratio (SEER) of 4.5 (sometimes written as 450%).

LIGHTING: The Recipe is created using a notional lighting system throughout the building which operates at 65 lumens per circuit watt. In reality, most modern lighting systems perform better than this. Lighting is also assumed to use occupancy and daylight controls to improve efficiency.

RENEWABLES: The recipe is calculated using PV panels at 5.3% of the gross internal area of the building. This means that, for a building of 1,000sqm, the TER and TPEC will be calculated using 53sqm of PV panels. Remember, you don’t need to install such a system, but it will be incredibly difficult to offset this requirement in any other way.

NOTE: For developers who work in England, you’ll be pleased to hear L2A England is not as stringent as this – email us for a copy of our Part L 2013 England Complete Guide: info@energistuk.co.uk

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U-VALUES: Design flexibility means you can build to U-Values which are higher than those stated in the Recipe. Part L sets out the absolute maximum U-Values you are allowed to construct a new commercial building to. These values haven’t changed since Part L was updated in 2006! (See Page 7)

SERVICES: The Building Services (heating, hot water, ventilation and lighting) play a much bigger role in the overall calculation than the building fabric (although this is still clearly important). Because of this, it is vital that you make sure all building services are designed to operate as efficiently as possible.

LIGHTING: For a standard commercial building, one of the biggest influences on CO2 emissions is the lighting design.

The good news is that lighting technology is constantly improving with innovative designs and controls.

The light levels you can design to work with a high-end LED arrangement can be as high as 100 lumens per circuit watt. Compare that to modern fluorescents at 80, energy saving lamps at around 50, and a typical incandescent or halogen light bulb at around 15 and you can see how far lighting has come in just a few years.

HEATING: When it comes to heat, the focus should always be on retaining it, not generating it.

Of course, whatever heating equipment you do use should be as efficient as possible. For example, we’d recommend you install a gas boiler with an efficiency of at least 91%.

Don’t forget about the hot water cylinder details either. If the cylinder isn’t adequately insulated then the savings of even the most efficient boiler will be lost through storage losses.

VENTILATION: In large commercial buildings, ventilation is essential to maintain high air quality; cycling stale air out and fresh air in, as well as reducing overheating.

RENEWABLE: The introduction of PV panels into the Recipe is going to be the biggest hurdle for developers, and the simplest (and probably most cost effective) solution will be to bite the bullet and install photovoltaic panels.

This may not appear to be the best approach, until you consider the alternative options: Boilers with integrated Combined Heat and Power (CHP) and wind turbines would reach the new target, but are they preferable to PV? Solar thermal may hit the targets, but only for buildings with a very high hot water demand (such as sports clubs with lots of showers).

Part L2AContinued

Part L2BNon-Domestic Refurbishments

2 Replace any light bulbs / fittings if the efficiency is less than 40 lumens per watt.

3 Install energy metering.

4 Upgrade the thermal elements of the building (walls, floors, roof, windows and roof lights).

5 Use on site low or zero carbon technologies.

6 Any other measures as listed in the Recommendations Report which came with the building’s Energy Performance Certificate.

If any of the above is seen to be practically and economically feasible, the improvements should be made as part of the overall building works. If in doubt, your Building Control Officer will be able to give you more specific details based on your development.

For existing commercial buildings which are undergoing extension or renovation work, Part L2B is likely to apply.

The U-Values are changing for extensions (or any heat loss element which is being knocked down and rebuilt). There are different U-Values depending on whether the building is ‘domestic in character’ or not. Buildings such as student accommodation and care homes would fall into this category.

There is a third set of maximum U-Values for existing elements which are being upgraded, rather than replaced.

See the full list of U-Values on Page 7.

CONSEQUENTIAL IMPROVEMENTS:Where you are extending a non-domestic building which is bigger than 1,000sqm, or where you are extending into a previously unheated space, you will need to follow the rules on Consequential Improvements – this means you will need to improve the overall efficiency of the existing building providing it is feasible to do so.Part L recommends looking at:

1 Upgrade / replace the heating, cooling and air handling systems if they are more than 15 years old.

22

PART L2:Again, another revision is expected in 2016, but the current stance of the Government is that commercial buildings will not reach a zero carbon until 2019 (or 2018 for publicly owned buildings).

The detail of how these targets are going to be met is currently a mystery, but expect a similar Allowable Solutions approach to be adopted.

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Looking aheadWhat’s next for our industry?

PART L1:Based on the Government’s own targets, the next revision of Part L is going to happen in 2016. Unless the goalposts are moved, we’ll be building to a zero carbon standard when this new set of regulations goes live.

By this, we’re not expecting every new house to generate all the power it needs, but we are expecting tougher targets in Part L, and the introduction of ‘Allowable Solutions’ – offsite carbon offsetting. The Zero Carbon Hub has published details on how this approach could work and it’s well worth checking this out.

FREE GUIDESWe have free guides available looking at many of the factors impacted by the Reg changes. Simply email us at info@energistuk.co.uk for your copy.

Zero Carbon Homes Avoid Falling Foul of Energy Regulations

Your Guide to Energy Efficient Commercial Builds

24

The End of CSH and BREEAMNational Development Management Policy binned

With the introduction of the new Part L, mandatory requirements for the Code for Sustainable Homes (CSH) and BREEAM across Wales have been scrapped.

Up until the end of July 2014, the Code was a requirement when building in Wales. Larger non-domestic buildings were required to meet specific BREEAM standards too.

But in an announcement which surprised many in the industry, the Welsh Government confirmed that planning policy TAN22 would no longer be applied to new developments.

This means that any development which is to be built to Part L 2014 will not need to be built to either the Code for Sustainable Homes or BREEAM. Whether new, voluntary equivalent versions of Code or BREEAM will be introduced at a later date is still not clear.

Before this July cut-off date, all new dwellings in Wales needed to be registered under the Code, with an 8% improvement in CO2 emissions over Part L 2010. But with the new, tighter emission targets which have been brought in under Part L 2014, new dwellings will still need to show an 8% reduction over Part L 2010, and non-domestic a 20% reduction, without any additional requirements.

In a statement from Carl Sargeant, the Welsh Minister for Housing and Regeneration, it has been confirmed that the Policy which requires Code and BREEAM is going to be abolished.

The Part L launch has been singled out as a key decision in this sudden change in policy. The statement reads: “I believe TAN22 has served its purpose now that the Welsh Government has control over Building Regulations which provide a more appropriate vehicle for setting building standards.”

Unlike in England, where local planners can opt in to the Code, councils in Wales are not being given the option. The statement continues: “I do not expect local planning authorities to develop policies for the use of local sustainable standards…”

Separate policies which reinforce the need to give further emphasis on the design of new developments to tackle causes of climate change, and which expect planners to assess strategic sites to identify opportunities for high sustainable building standards will still apply.

Although this would suggest things are going to get easier when it comes to sustainability in the Welsh housing market, the transitional arrangements aren’t so black and white.

Existing developments, or those which are approved before July 31st 2014, may still need to comply with all the relevant Code or BREEAM requirements, but it is the decision of planning departments at a local level whether to continue to enforce the requirements on existing sites, or to wind the scheme up overnight.

It is understood that the Code for Sustainable Homes will be phased out of England at the start of 2015, although no official documents have been released to confirm details as yet.

Wales is committed to changing Part L in future to ensure that all new buildings are ‘nearly zero carbon’ by 2019 – the next planned updated to the Building Regulations for both England and Wales is in 2016.

The End of CSH and BREEAM(continued)

Policy 4.12 of Planning Policy Wales had three elements: RETAINED: Designing For Climate Change

Policy to reinforce the need to give further emphasis on the design of new developments to tackle the causes of climate change and to adapt to the current and future effects of climate change.

SCRAPPED: National Development Management Policy

Policy which expects new homes and major new non-residential developments to achieve a minimum sustainable building standard under CSH and BREEAM.

RETAINED: Strategic Sites

Policy that expects local planning authorities to assess strategic sites to identify opportunities for higher sustainable building standards and include relevant policies in their Local Development Plan.

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DWELLINGS Floors Walls Roofs Glazing

New Build 0.25 0.30 0.20 2.00

Extension/Replace 0.22 0.28 0.18 1.60

Renovation 0.25 0.30-0.55 0.16-0.18 1.60

COMMERCIAL Floors Walls Roofs Glazing

New Shell 0.25 0.35 0.25 2.20

Extension 0.22 0.28 0.18 1.80

Upgrade 0.25 0.30 0.18 1.60

What has happened in England?England was the first region of the UK to jump on board with the new SAP and Part L details, and all new developments since April 2014 have been measured under this latest set of documents.

RESIDENTIALThe calculation technique for the Design and Target Emission Rates (DER / TER) are identical. But a second, mandatory target has been introduced to England, called the Fabric Energy Efficiency.

This focuses on building fabric and construction only, and ignores services (such as heating and lighting efficiencies). Both the TER and the Target Fabric Energy Efficiency (TFEE) must

be met, otherwise the dwelling will not comply with Part L.

By introducing this TFEE assessment, Westminster decided the leave the maximum U-Values for L1A at the 2010 standard, although in reality developers will need to do much better than these to make sure they comply.

The new Fabric Energy Efficiency target which is being brought in for England is not required in Wales.

Instead, the limiting U-Values for Wales are being reduced (whereas in England they have remained at 2010 levels).So the new U-Values for Wales are:

Limiting U-Values for renovations vary depending on existing construction.

COMMERCIAL:There’s no nice way of saying this, but with only a 9% reduction over apart L 2010, and with no TPEC requirement, new non-domestic buildings in England have much easier targets to reach when compared to new buildings in Wales.

Upgrade U-Values vary depending on existing contruction.

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What will happen in Scotland?In Scotland, the SAP and SBEM assessments are staying the same until 2015. A different set of Elemental Recipes are used. The idea of using a Recipe to calculate targets is not new to Scotland – they have been using this approach since 2007.

There are five different Recipes for new build dwellings, depending on the type of heating system being installed.

For the domestic sector, the Recipe is quite similar to those being used in England and Wales, except there is the addition of solar thermal panels (the amount depends on how big the house is).

Limiting U-Values in Scotland also differ from other countries in the UK.

The current set is listed here:

DWELLINGS Floors Walls Roofs Glazing

New Build 0.20 0.25 0.18 1.80

Extension 0.18 0.22 0.15 1.60

Renovation 0.25 0.30 0.25 1.60

COMMERCIAL Floors Walls Roofs Glazing

New Build 0.22 0.27 0.20 2.00

New Shell only 0.20 0.23 0.15 1.60

Conversion 0.25 0.30 0.25 1.60

Extension 0.20 0.25 0.15 1.60

COMMERCIAL:When calculating the Target Emission Rate in Scotland, a 2002 specification building is modelled in the SBEM software, and the result is then halved. The actual specification must be shown to equal, or lower than this target.

The SBEM methodology is the same as for the rest of the UK. Only the maximum U-Values, and the way the Target Emission Rate is calculated are different.

To request your free complete guide to the Scottish Building Regulations available in 2015 – simply email info@energistuk.co.uk

What people say about us96.3% of our customers say we meet or exceed their project objectives

99% rate their Energist Experience as Very Good or Good.

The biggest measure of customer satisfaction is the Net Promoter Score, which evaluates how likely a customer would be to recommend us to another. We have a great 79% of clients who are actively promoting us, which is an outstanding amount.

And here’s what some of them have to say:

@EnergistUK/EnergistUK

What can I say, other than your company is one of the best I have had to deal with. I would like to take this opportunity to thank you all for a great service and look forward to working

with you in the not too distant future.

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customer approach.

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so thanks for your help.

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Part L1A 2014 Summary

16

We know there are hundreds of great ways of building the perfect house. This recipe is a sure-fire way of passing the Part L taste test every time!

FEEDS: For the whole family

INGREDIENTS: For the casing:

0.13 U Values of floor 0.13 U Values of roof 0.18 U Values of walls* 1.40 U-Value for windows

and rooflights, 1.20 for semi-glazed doors

and 1.0 for solid doors** Thermal Bridging - Y Value of 0.05

*Aim for no heat loss through party walls **Glazing = 25% of total floor area

For the filling: 89.5% mains gas boiler with zone control

(where feasible) and weather compensator. Hot water cylinder (if being fitted) to have

heat loss no worse than 1.39 kWh daily. 100% low-energy lighting 5.0 predicted air test Extraction fans where appropriate

WALES

YOUR RECIPE FOR COMPLIANCE@EnergistUK

Maximum U-Values for new dwellings, renovations

or extensions.

These are:

NEW BUILD: Floor 0.18Wall 0.21

Party Walls 0.20Roof 0.15

Openings 1.60

REFURB: Floor 0.25Wall 0.30

Roof (insulation in ceiling) 0.16Roof (all other cases) 0.18

EXTENSIONS: Floor 0.18Wall 0.21Roof 0.15

Glazing 1.60

Other limiting values:

AIR LEAKAGE TESTS: Results must be no higher than 10 m3/hm2 (although it’s likely

you’ll need to go lower than this to pass the SAP)

LOW ENERGY LIGHTING: At least three quarters of fixed light outlets must be fitted with

low energy bulbs

HEATING: Each type of heating

system must meet limiting efficiencies. These include

gas and oil boilers (88%), heat pumps (2.5 CoP), and wood

burning stoves (65%).

VENTILATION: If Heat Recovery systems are

installed, the efficiency should be higher than 70%.

U-VA LUES

Start with the casing… Construct the shell using your floor, wall and roof materials. A floor of 0.13 could be achieved with 150mm PU under a screed. A roof of 0.13 could include 350mm mineral wool quilt. A 0.18 wall could be achieved using brick and block with 140mm cavity with 90mm PU Foam Board, or by using SIPs or a timber frame construction. Don’t forget to use approved thermal bridging details and pipe insulation to prevent unnecessary heat loss.

Include your openings… the sunnier the better! High spec double glazing can achieve 1.40, but expect to use triple glazing if you go much lower.

Install your desired ventilation, heating and lighting systems. Remember to stick to or improve on the recipe details for all building services.

Arrange for your air test to be completed – remember to aim for 5 or lower.

Store your SAP and EPCs in a safe place for future reference.

Your house is ready to serve immediately.

S U M M A RY

CHEF’S TIP:You can vary the recipe to taste, but you need to keep the ingredients balanced.

For example, you can decrease your wall thickness and reduce insulation, but you

might need to offset this with flue gas heat recovery. Alternatively, you could cut back on your heating controls but you

might need to install a mechanical ventilation system, especially if

your air permeability is below 5.

CHEF’S TIP: If you’re not on the gas grid, the target will be adjusted depending on

the fuel of your main heating.

CHEF’S TIP:If you’re not already, we recommend you research and adopt some form of thermal

bridging details for all new dwellings, as this is one of the key ingredients in the recipe.

The most common junctions are the Accredited Construction Details, but as these

perform worse than the details used in the Elemental Recipe, it’s worth finding out if you can build your junctions to a higher

standard. Other details are available online, from manufacturers, or can

be calculated for your specific construction.

t: 08458 386 387e: info@energistuk.co.uk

w: www.energistuk.co.uk

Part L2A 2014 Summaryt: 08458 386 387

e: info@energistuk.co.ukw: www.energistuk.co.uk

@EnergistUK

Maximum U-Values for commercial buildings,

renovations andextensions. These are:

NEW BUILD: Floor 0.25Wall 0.35Roof 0.25

Openings 2.20

REFURB: Floor 0.25

Wall (Retro-filling empty cavity) 0.55

Wall (all other cases) 0.30Roof (insulation in ceiling) 0.16

Roof (all other cases) 0.18

EXTENSIONS “DOMESTIC IN CHARACTER”:

Floor 0.18Wall 0.21Roof 0.15

Glazing: 1.60

EXTENSIONS - ALL OTHER CASES:

Floor 0.22Wall 0.26

Roof (insultion in ceiling) 0.16Roof (all other cases) 0.18

Glazing: 1.80

BPEC / TPEC:The Target Primary Energy

Consumption applies to all new commercial buildings in

Wales, as well as the Target Emission Rate.

U-VA LUESS U M M A RYThere isn’t a one-size-fits-all answer for constructing a compliant commercial building to Part L 2014 standards, but this elemental recipe is certainly a good place to start. An SBEM is a great way of experimenting with different ingredients to find your preferred method.

FEEDS: Anyone - from the smallest corner shop to the largest of factories

INGREDIENTS: For the casing:

0.22 U-Values of floor 0.26 U-Values of wall 0.18 U-Values of roof 1.50 U-Value for vehicle access doors 2.20 U-Value for other external doors  Windows should have a U-Value of 1.6 with 10% framed area The G-Value is 40% and light transmittance is 71% Rooflights should have a U-Value of 1.8 with 15% framed area The G-Value is 55% and light transmittance is 60%

For the filling: You can fill your building with a myriad of heating systems

- this recipe assumes you’re using a gas boiler. Use a 91% efficient mains gas boiler to provide all heating

and hot water. Use a lighting system throughout the building with an

efficiency no lower than 65 lumens per circuit watt Lighting should be made more efficient by using occupancy

controls and daylight controls

The Recipe for Air Test Targets:

Buildings with rooflights only

for natural light:

All other cases:

Building area <250m2 7 5

Building <3,500m2 7 3

Building <10,000m2 5 3

Building >10,000m2 3 3

Ventilation: Based on 70% efficient heat recovery ventilation system with

central specific fan power of 1.8 w/l/s and terminal unit of 0.3 w/l/s

Cooling: Where a building has cooling, the recipe operates at a SEER

efficiency of 4.5 if part of an air conditioned, or 2.7 if mixed mode.

Renewables: PV panels - array size of 5.3% of the total floor area.

CHEF’S TIP:If the building is not on the mains gas grid, or you’re using a different type of

heating system, the Elemental Recipe will change to more

accurately reflect your actual heating system.

Start with the casing... Construct the shell using your floor, wall and roof materials. A roof of 0.18 can be achieved with 250mm mineral wool. A cavity wall of 0.26 can be met with a fully filled 300mm wall with thermal blocks. If you are using prefabricated materials, it should be quite straightforward to surpass these values, and improve your recipe.

Openings... Solar gains from south facing windows are a good way of reducing heating demand for your building, but if you’re planning on using a cooling system, too much south facing glass will increase cooling use, and increase the overall emissions

CHEF’S TIP:You can vary the recipe to taste, but you need to keep the ingredients balanced.

For example, you can use a natural ventilation system instead of heat recovery, but

you’ll need to compensate for this – maybe by using a higher efficiency lighting system.

As a general rule, the building fabric doesn’t have as much of an impact

as the building services.

YOUR RECIPE FOR COMPLIANCE

WALES

CHEF’S TIP:Depending on your building use,

services will be assessed differently in SBEM. For example, a building which uses a lot of hot water – such as a sports hall with a large shower block – would

benefit from solar water heating... but this type of system would

be next to useless on a building such as a warehouse, where the

hot water demand is zero.

Install your preferred heating, hot water, ventilation and lighting systems. Remember to look at improving on the details in the recipe wherever possible.

Did you notice there are renewable technologies in the recipe? If you were to install more on your building, you’ll show an improvement over the recipe. It will be extremely difficult to meet the recipe without renewables.

Next, arrange for your air test to be completed on the building. Remember the recipe target changes depending on the building size, and the type of building.

Store your SBEM and EPCs in a safe place for future reference.

Your commercial building is ready for use. Serve immediately.