YOUR COMPLETE GUIDE TO

PART L 2013All you need to know about energy

efficiency regulations from April 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 Fabric energy efficiency Extra focus on insulation and air tightness

6 Limiting U-Values Design flexibility over tougher insulation requirements

8 Bridging the gaps SAP is focused on heat loss from thermal bridges

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 - England How to comply with the new targets

16 Feasibility checking High Efficiency Alternative Systems

18 Energy statements Helping meet local planning policies

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

21 Part L2A Changes for non-domestic new builds

24 Part L2B Non-domestic refurbishments

25 Looking ahead What’s next for our industry?

26 What will happen in Wales?

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

are unchanged for new

commercial buildings, for

renovations and for

extensions.

These are:

NEW BUILD:

Floor 0.25

Wall 0.35

Roof 0.25

Openings 2.20

REFURB:

Floor 0.25

Wall 0.30*

Roof (insulation in ceiling) 0.16

Roof (all other cases) 0.18

*Relaxed to 0.55 when

retro-filling an empty cavity

EXTENSIONS:

Floor 0.22

Wall 0.28

Roof (insulation in ceiling) 0.16

Roof (all other cases) 0.18

Openings 1.80

DFEE / TFEE:

The Target Fabric Energy

Efficiency does not apply to

commercial buildings – only

new build dwellings.

BPEC / TPEC:

The Target Primary Energy

Consumption does not apply to

commercial buildings in

England.

U-VA LUES

S U M M A RY

Part L2A 2013 Summary

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

compliant commercial building to Part L 2013 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.

Results will vary where other heating systems are used!

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 60 lumens per circuit watt

Lighting should be made more efficient by using occupancy

controls and daylight controls 100% low-energy lighting

5.0 predicted air test

Extraction fans where appropriate

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.

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

ENGLAND

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 aren’t any renewable or low carbon

technologies in the recipe? If you were to install some on your

building, you’ll show an improvement over the recipe.

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.

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

ENGLAND

t: 08458 386 387

e: info@energistuk.co.uk

YOUR RECIPE FOR COMPLIANCE

@EnergistUK

Maximum U-Values

are unchanged for new

dwellings, renovations

or extensions

These are:

NEW BUILD:

Floor 0.25

Wall 0.30

Roof 0.20

Openings 2.00

Party Walls 0.20

REFURB:

Floor 0.25

Wall 0.30

Roof 0.16

Sloping roof insulation 0.18

Openings 1.60

EXTENSION:

as ‘Refurb’ except

Floor 0.22

Wall 0.28

Commercial U-Values

haven’t changed either:

Floor 0.25

Wall 0.35

Roof 0.25

Openings 2.20

DFEE / TFEE:

If you build the fabric of

your building in line with

the Elemental Recipe, you

will comply with the TFEE

by 15%. This means you have

some scope for using a lesser

spec in exchange for better

services, but don’t think you

can use limiting U-Values only,

that certainly will not work!

Remember, the TFEE applies to

new domestic buildings only.

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.

Part L1A 2013 Summary

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.

3

Welcome messagefrom Sarah Fenwick, Managing Director of Energist UK

There’s plenty I love about English

contruction: world class talent, cutting edge innovation and an inspiring heritage. It also has its downsides: unpredictable weather, regional quirks and an encyclopaedia of regulatory jargon.

The official documents do a better job confusing than clarifying, and that’s coming from a team who reads them more times than we care to remember! So today, we’ll make your world better by making it a little simpler.

In this guide, you’ll find everything you need to know about Part L and efficient, sustainable construction in England. It’s no nonsense, to the point information on which regulations and tests you need to pay attention to from the first to last stage of your build, along with a peek at the future.

This project-saving advice will be right at your fingertips whenever you need it and we’re just a call away if you need more.

SHORT OF TIME?What we are really saying is if you are short of time today, just read the sections that look like this. The Complete Guide to Part L 2013 will give you a good understanding of regulations and may prove essential to your business.

Regulation changes - what’s newLower emission rates, new targets and balancing acts

THE BUILDING REGULATIONSOf all the different Approved documents of Building Regulations, Part L is the one which gets modified the most. The Government’s Zero Carbon Homes target is just a couple of years away, and the only way we stand a chance of hitting this goal is if Part L and the associated emission rate become tougher to achieve.

The most recent update to Part L was in April 2014, under the title Part L 2013. This brought in a new Target Emission Rate which is typically 6% tougher than Part L 2010 for new dwellings in England, and just under 9% tougher for non-domestic buildings.

This was a noteworthy occasion in that Part L 2013 is the first Approved Document to have specific English and Welsh versions. The Welsh Government in Cardiff has taken control of the country’s Building Regulations from Westminster, and will go live in July 2014.

This means developers who work on both sides of the border will have different regulations to contend with – if you’d like a copy of our free guide to the Welsh 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 ‘2013 Elemental Recipe’.

A one-size-fits-most 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 English and Welsh recipes.

4

Fabric Energy EfficiencyExtra focus is placed on insulation and air tightness

Aside from the enhanced Target Emission Rate, a second compulsory target has been brought in - the Fabric Energy Efficiency (FEE). This will apply to new dwellings in England only.

The FEE – which has been lifted and adapted from the Code for Sustainable Homes - has been included into Part L to take into account an historical ‘loophole’ with the Target Emission Rate…

Up until now, you could in theory build a house to a relatively poor standard of insulation (when compared to today’s best practice), and then compensate using a low carbon resource like PV panels or a heat pump. This would meet the Target Emission Rate, but doesn’t follow the idea of conserving fuel.

This is where FEE comes in. Measured in kWh/m2/year, FEE assess the heating demand of a property.

It is calculated by the SAP Methodology and takes into account building fabric, insulation levels, air permeability, solar, internal gains and thermal bridging.

HOW DO YOU PASS THE FEE TARGET?See the ‘Elemental Recipe’ poster included with this guide.If you build to this specification, you would exceed the

Target Fabric Energy Efficiency (TFEE) by 15%. The Government has built-in this buffer of 15% to allow for greater design flexibility. We expect this target will be tightened up as years go by.

Remember that building services (heating systems, lighting, solar panels etc) have no impact on the FEE score whatsoever, so you need to focus on reducing the heating demand through passive measures only, to meet the target.

To demonstrate compliance with Part L 2013, you need to meet both the TER and TFEE. It would be possible, if you built a house with high levels of insulation and then installed a high carbon heating system, to pass the TFEE but fail the TER. Likewise; a high efficiency heating system in a poorly insulated house may fail the TFEE but pass the TER.

SHORT OF TIME?To comply with FEEs, you need to focus on U-Values, air tightness and the orientation of your glazing. You need to comply with both the TFEE and the TER in order to meet Part L 2013. This only applies to new dwellings in England.

5

Limiting U-ValuesDesign flexibility over tougher insulation levels.

When Part L 2013 was being drafted, there was talk of all limiting U-Values dropping to force us into adding more insulation into our new buildings.

This hasn’t happened. In fact, all limiting U-Values remain exactly where they were in the 2010 version of Part L (see next page).

But, as we have already covered, the overall Target Emission Rates are being made more stringent. So, how can you change one without the other? It’s all tied in with the term ‘design flexibility’.

EXPLANATIONWhen your dwelling is assessed in SAP, the Target Emission Rate and Target Fabric Energy Efficiency are created using the dimensions of your dwelling, but based on the specification as listed in 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.

SHORT OF TIME?Design Flexibility means you have the freedom to construct any heat loss element to the maximum standards shown on the next page. But in order to pass Part L, you need to compare your specification to the Elemental Recipe. If any parts of your spec are worse than the recipe, you’ll need to compensate by making improvements elsewhere.

6

An example wall section

This is the full set of U-Values, expressed in W/m2K, which you are allowed to build to under Part L 2013. These U-Values apply to England only.

ENGLAND PART L U-VALUES

DWELLINGSFloors Walls Roofs Glazing

L1A New Build 0.25 0.30 0.20 2.00

L1B Extension 0.22 0.28 0.18 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 2.2

L2B Extension 0.22 0.28 0.18 1.80

L2B Upgrade 0.25 0.30 0.18 1.80

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, the maximum U-values allowed for upgrading existing walls varies. If it is an uninsulated cavity, it should be upgraded to achieve 0.55.

When renovating an existing roof under Part L1B, a U-Value of 0.16 should be achieved where insulation is laid horizontally within the loft space.

Upgrade U-Values vary depending on existing construction

7

Limiting U-ValuesContinued

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 this date, builders had to show they were constructing junctions of their buildings to a particular standard to ensure 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 have got used to the idea of building to this better standard, a more detailed assessment has been released into the updated SAP software.

Up 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 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 these up, and others, online:

Accredited Construction Details Enhanced Construction Details Constructive Details

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 block work 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.

8

A thermal bridge

9

Keeping hot water hotMore insulation required for pipework

A new section of SAP has been brought in to more accurately measure 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 is insulated

All visible pipework insulated No insulation on the pipework at all

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

SHOWERSUnder 2010 regs, SAP hasn’t paid any attention to the type of showers you install 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.

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.

10

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 being completed, 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 these U-Values are identical to the limiting U-Values of 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 details, 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 the proposed extension will perform no worse than 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.

RENOVATIONS & CHANGE OF USE:Existing buildings which are undergoing renovation work should be measured under Part L1B. Page 7 lists the U-Values which should be achieved for any elements which are being upgraded.

It is worth noting this only applies if 50% of the total surface of the individual element, or 25% of the total building envelope, are being upgraded.

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 costs more than the anticipated savings 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.

11

CONSEQUENTIAL IMPROVEMENTSWhile the finer points of Part L were being ironed out, there was a section in Part L1B called ‘Consequential Improvements’.

If a developer was building an extension they would need to ring-fence a minimum of 10% of the total budget of the works to be spent on upgrading the existing house.

By bringing in this requirement, developers would be required to make improvements to the energy efficiency of existing homes by looking at upgrading items such as roof insulation, heating systems or changing to double glazing.

However, Consequential Improvements never made it into the final draft (for England anyway!).

Consequential Improvements will apply to extensions on large, commercial buildings, but this was a feature of the previous version of Part L, so hopefully will not come as a shock to anyone.

Part L1BContinued

12

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 not looking 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.

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 55c degrees or higher, but systems which run at lower temperatures are known to be more efficient. If your heating system operates at 45c or even 35c degrees, 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 an MCS certificate from the installer. This is seen as proof that your system was installed by a competent tradesperson, and therefore it is assumed the system will operate more efficiently.

14

Elemental recipes - EnglandHow 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) and the Target Fabric Energy Efficiency (TFEE). In theory, if you follow this ‘Recipe’ word for word, you should show full compliance with the new Part L. It’s also referred to as Model Designs under 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 England 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 20 for more details).

SIZE AND SHAPE: The TER and TFEE are 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.

15

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 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 - EnglandContinued

16

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.

17

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.

Remember this is not the same as an Energy Statement (see Page 18). Energy Statements are a planning condition which may apply to your site depending on council requirements.

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

Feasibility checkingContinued

18

Energy statementsHelping meet local planning policies

It’s now quite a common council requirement, particularly in urban areas, to ask developers to provide an Energy Statement as part of their planning application for new sites.

The details for an Energy Statement – sometimes referred to as Feasibility Studies – depend completely on the councils own Local Planning Policies and requirements, and as such there’s no nationally agreed policy about format or how to calculate the maths which back up the claims in the reports.

Energy Statements can be requested on both domestic and commercial developments. They are usually (but not exclusively) asked for on larger sites.

Some councils ask for a particular reduction against the Part L Emission Rate, whilst some councils ask for a certain percentage of energy/carbon emissions to be reduced through the use of low or zero carbon technologies only.

Some councils may also request that a Code for Sustainable Homes assessment be completed on a development.

Some Local Planning Authorities are happy to rely on Building Regulations (Part L) and will not ask anything further of you. If you notice a paragraph in your planning conditions which refers to reductions in energy use or carbon emissions above and beyond building

regulations, chances are you’ll need one of these reports. It is not a document requested by your Building Control department.

Confused yet? Here are just some of the planning policies you may be asked to achieve (correct at time of press and conditions may alter depending on size of development):

LONDON: Show a 40% reduction in carbon emissions over Part L using a Fabric First approach and then adopting low carbon and renewable technology

BRISTOL: Show a 20% reduction in carbon emissions over Part L, but only by using technology which generates onsite energy

WIGAN: Show a 15% reduction in regulated energy use through the use of decentralised, renewable and low carbon energy sources

MID DEVON: Show a 14% reduction (this one rises by one per cent every year) in regulated energy from decentralised, on site renewables or low carbon sources

BRACKNELL: Show a 10% reduction in carbon emissions over Part L, and also show a 20% reduction in regulated energy use from on-site energy generation.

19

As the requirements of Energy Statements change from council to council, it’s impossible to give one simple answer about how to sign off this condition. We take the SAP and SBEM methodologies which we know inside out, and then as a general rule we would go through the following process:

Firstly, we would start by completing SAP (or SBEM) assessments for your development based on notional values and heating details. This is called the ‘Baseline’ assessment.

Next, we look at your proposed specification, and from here we can usually show an improvement against the Baseline. This is sometimes referred to as the Fabric First approach, or the ‘Improved’ assessment.

If the above shows a big enough improvement, some councils will be happy for us to stop there. But if you need further improvements, or if you need to adopt low / zero carbon technologies, we’ll continue...

We’ll complete a Feasibility Check on your site which looks at which types of low and zero carbon technologies may be practical for your site.

We’ll then draw up a list of those technologies which we believe are

the most feasible, and create some sample scenarios showing how much of an improvement can be met by installing these technologies.

We’ll summarise the Energy Statement by showing a handful of scenarios and recommending the best approach to take.

In completing this survey, our aim is to take the headache out of Energy Statements, at the same time as showing how your SAP / SBEM assessments can show full compliance with Part L.

The Government’s response to the Housing Standards Review has indicated that Local Planning Authorities will be able to set site specific renewable energy targets but not additional standards on building fabric.

Energy statementsContinued

20

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 changes. If you would like to attend one of our events please email:cpd@energistuk.co.uk

21

Part L2AChanges for non-domestic new builds

The Target Emission Rate is once again going to be calculated using an ‘Elemental Recipe’ – if you build to this Recipe, you should achieve compliance, however it’s not a one size fits all approach, especially with the building services, which will often change depending on the intended use of the building.

The key details of the recipe are:

HEAT LOSS FLOORS: 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.

HEAT LOSS WALLS: 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: 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

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 is being lowered as part of the changes to Part L – so we’ll typically see this target reduce by 9%.

22

Part L2AContinued

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%).

SHORT OF TIME?Don’t look for a one-size-fits-all in the non-domestic world. For example a solar thermal system works very effectively on a sports hall with lots of showers, as there is a very high demand for hot water. A large solar thermal system attached to an office block will be nowhere near as effective, as the only hot water requirement is likely to be for cups of tea and washing hands.

LIGHTING: The Recipe is created using a notional lighting system throughout the building which operates at 60 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: No low carbon or renewable technologies are used in the English Elemental Recipe.

NOTE: There are more substantial changes coming into play in Wales - email us at info@energistuk.co.uk to request your free copy of the Welsh guide.

23

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.The more light you can get for your watt doesn’t just mean lower CO2 levels and a better SBEM result; it can also lead to significant savings in energy bills.

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 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.

The problem is that ventilation will often remove heat along with unwanted stale air. By installing a system that recovers heat from extracted air, you can reduce the load for the heating equipment.

Part L2AContinued

24

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.

There are no changes to the Fabric Standards of Part L2B when compared to the 2010 version, which means if you are building compliant extensions already, you don’t need to worry!

If you are changing the building services as part of the renovation works, you need to make sure these comply with the Non-Domestic Building Services Compliance Guide.

CONSEQUENTIAL IMPROVEMENTS:Again, this section in Part L2B has not changed. It only impacts non-domestic buildings over 1,000m2 where they are being extended or you are installing a new cooling system or increasing the capacity of an existing cooling system.

In these cases, the developer needs to consider ways of reducing the emission rate of the existing part of the building. Part L recommends looking at:

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

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.

25

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.

Avoid Falling Foul of Energy Regulation

Expert advice to completing a compliant construction project

From Sarah FenwickFounder of Energist

Your Guide to Energy Efficient

Commercial Builds

From Steve Hull,Commercial Energy Assessor at Energist

Avoid Falling Foul of Energy Regulations

Expert advice to completing a compliant construction project

From Sarah FenwickFounder of Energist

“The Team that de-risks the Regs”

making your world better

Zero Carbon Homes:Too Soon?

From Stuart Clark,Technical Manager at Energist

Avoid Falling Foul of Energy Regulations

Expert advice to completing a compliant construction project

From Sarah FenwickFounder of Energist

“The Team that de-risks the Regs”

making your world better

FREE GUIDESWe have free guides available looking at many of the factors impacted by the reg changes. Simply visit our website www.energistuk.co.uk to register for your copy.

Zero Carbon Homes Avoid Falling Foul of Energy Regulations

Your Guide to Energy Efficient Commercial Builds

DWELLINGS Floors 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* n/a

L1B Replace 0.15 0.21 0.15 1.60

COMMERCIAL Floors Walls Roofs Glazing

L2A New Shell 0.25 0.35 0.25 2.20

L2B Extension (Comm)+ 0.22 0.26 0.15-0.18 1.80

L2B Extension (Resi)+ 0.18 0.21 0.15-0.18 1.60

26

What will happen in Wales?One by one, the Welsh Assembly is writing its own version of Building Regulations, for use only in Wales.

The first point to note is that Part L Wales goes live July 31st 2014. If you submit your Building Control Application before this date, you will be allowed to build to the previous version of Part L.

In many respects, the English and Welsh Part L documents are similar, but at the same time there are some noticeable changes.

RESIDENTIALThe new Fabric Energy Efficiency target which is being brought in for England (Page 5) is not required in Wales.

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

COMMERCIALIn England the Target Emission Rate for new commercial buildings is being lowered by 9%. In Wales, this target is being lowered by 20%. They have achieved this larger reduction by including PV panels into the Welsh Elemental Recipe for new commercial buildings.

Also a new, second, mandatory target is required – the Target Primary Energy Consumption (TPEC). This measures the efficiency of the building services (heating, cooling, lighting and ventilation) only. TPEC does not look at the quality of the building fabric.

To register for our free complete guide to the Welsh building regulations – simply email info@energistuk.co.uk

+U-Values for extensions to existing commercial buildings vary depending on whether a building is ‘domestic in character’ or not.*Renovation U-Values vary depending on existing construction

27

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

SCOTLAND SECTION 6 U- VALUES

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 register for our 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

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so thanks for your help.

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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

ENGLANDt: 08458 386 387

e: info@energistuk.co.uk

YOUR RECIPE FOR COMPLIANCE@EnergistUK

Maximum U-Values are unchanged for new dwellings, renovations

or extensions

These are:

NEW BUILD: Floor 0.25Wall 0.30Roof 0.20

Openings 2.00Party Walls 0.20

REFURB: Floor 0.25Wall 0.30Roof 0.16

Sloping roof insulation 0.18 Openings 1.60

EXTENSION: as ‘Refurb’ except

Floor 0.22Wall 0.28

Commercial U-Values haven’t changed either:

Floor 0.25Wall 0.35 Roof 0.25

Openings 2.20

DFEE / TFEE:If you build the fabric of

your building in line with the Elemental Recipe, you will comply with the TFEE

by 15%. This means you have some scope for using a lesser spec in exchange for better services, but don’t think you

can use limiting U-Values only, that certainly will not work!

Remember, the TFEE applies to new domestic buildings only.

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.

Part L1A 2013 Summary

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

@EnergistUK

Maximum U-Values are unchanged for new

commercial buildings, for renovations and for

extensions.These are:

NEW BUILD: Floor 0.25Wall 0.35Roof 0.25

Openings 2.20

REFURB: Floor 0.25Wall 0.30*

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

*Relaxed to 0.55 when retro-filling an empty cavity

EXTENSIONS: Floor 0.22Wall 0.28

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

Openings 1.80

DFEE / TFEE:The Target Fabric Energy

Efficiency does not apply to commercial buildings – only

new build dwellings.

BPEC / TPEC:The Target Primary Energy

Consumption does not apply to commercial buildings in

England.

U-VA LUESS U M M A RY

Part L2A 2013 Summary

There isn’t a one-size-fits-all answer for constructing a compliant commercial building to Part L 2013 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 60 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.

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 COMPLIANCEENGLAND

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 aren’t any renewable or low carbon technologies in the recipe? If you were to install some on your building, you’ll show an improvement over the recipe.

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.