BUILDING REGULATIONS Part L

Building Regulations 2006 L1 for Dwellings
Building Regulations 2006 L2 for non-domestic buildings
Building Regulations 2002


Building Regulations - Part L1A L1B and L2A L2B (approved document L) Conservation of fuel and power in England and Wales took effect on 6 April 2006

OUTLINE OF 2006 REGULATIONS for DWELLINGS
A. New dwellings (approved document L1A)

These are the main ways in which compliance is calculated:
1. Calculate the TER (Target CO2 Emissions Rate) for the dwelling, by substituting in the designed dwelling standard U-values (Table 2 on page 19 of the Approved Document) , glazed area, air infiltration, heating and fuel , and apply an improvement factor (currently 20%)
2. Calculate the DER (Dwelling CO2 Emissions Rate) with the parameters as required by the actual design, subject to some limiting conditions.
If the DER is better, i.e less than, the TER, the dwelling complies with this part of Part L.
3. Calculate the SAP rating.
4. Check internal and external lighting meets requirements.
5. Calculate summer condition to demonstrate that there is no tendency to high summer temeratures.

The assessment should be made for the design and again for the completed building.

B. Work in existing buildings (approved document L1B)

1. EXTENSIONS TO DWELLINGS:
a) Approach 1 - very simple
If the openings in the extension are less than 25% of floor area of the extension, ensure than U-values in extension meet standard values (Table 4 on page 22).

b) Approach 2 - quite flexible
Show that the average U-value of the extension is better than the extension would be with standard U-values and openings area.

c) Approach 3 - most flexible
Show that the CO2 emissions from the whole extended dwelling are no more than they would be for the dwelling with a notional extension built to standard U-values and openings. (Any improvement in the main dwelling cannot be included in this calculation, but is dealt with separately as below).

2. MATERIAL CHANGE OF USE:
If a dwelling is made in an existing building:
a) Simple method
New and replacement elements must meet thermal standards (Table 4 on page 22).
Retained elements must be upgraded if they are outside U-value threshold values (Table 5 on page 23).
b) More flexible method
Show that the total CO2 emissions are no worse than if the rule above had been followed. This allows for renewable energy sources, etc, to offset U-values.

3. MATERIAL ALTERATIONS:
When a dwelling is altered:
a) Show that retained and new thermal elements meet U-value criteria of Table 4 on page 22.
b) Ensure that retained thermal elements are upgraded if outside threshold limits of Table 5 on page 23, if economically feasible.

NOTES:


1. U-Value criteria:

The regulations look separately at:
a) Individual parts of the roof, walls and floors (i.e roof type 1,2 etc)where these differ in U-value.
b)The area-weighted average U-value of the whole roof, wall and floor.
There are different limits for each type and for the average.

2. Air infiltration:

For existing buildings a method of compliance is for work to be to Robust Details.
For dwellings in new buildings:
Either show by testing that air infiltration is less than 10 m3/hm2 at 50Pa
Or show by testing it is no worse than the infiltration used in the compliant DER calculation
Or (if no more than 2 dwellings of the type on a site) use a design value of 15 m3/hm2 in the DER. Compared with figure of 10 m3/hm2 this will necessitate improvements elsewhere to compensate.


OUTLINE OF PART L2, for NON-DOMESTIC BUILDINGS



L2A NEW BUILDINGS
For new buildings calculations are required using BRE's SBEM program, or an approved equivalent. SBEM calculates all the L2 requirements for new buildings except for solar gain under Clause 64. I provide SBEM calculations and include further calculations for solar gain, to CIBSE publication TM37 as approved in Part L2 . I provide the stipulated Compliance Checklist.
L2A permits re-submission of calculations 'as built' on completion, showing that the building still complies, if air permeability is poorer than designed.

PART L2B EXISTING BUILDINGS
1) MATERIAL CHANGE OF USE
For a change of use, the approved document allows a means of compliance under L2b Clause 36. This sets standards for U-values of thermal elements and for heating, hot water , and lighting services.
If it is not possible to achieve compliance under Clause 36, greater flexibilty is allowed under Clause 37. For this calculations have to show that the CO2 emissions are no greater than if Clause 36 had been followed. This requires two sets of SBEM calculations, one as proposed and the other notional to Clause 36.

2) MATERIAL ALTERATION
For alterations, the approved document allows compliance under L2b Clause 39. This sets standards for U-values of altered thermal elements and for altered heating, hot water , and lighting services.
An SBEM calculation is not required. In difficult cases it is possible to provide an economic feasibility assessment to support a proposal.

3) EXTENSIONS
In accordance with L2b clause 25, for an extension of over 100m2 and more than 25% of floor area of the existing building an L2a calculation should be provided. Additionally, if the existing building has more than 1000m2 of floor area, consequential improvement in the existing building is necessary per Section 1 of L2b.
My calculations will include 1) SBEM output and 2) calculations for solar gain to TM37, required under L2a Clause 64, plus the Compliance Checklist



2002 Regulations Part L Conservation of fuel and power in dwellings

Outline of 2002 Regulations (for historic information only)



Building Regulations - Part L1 (approved document L1) in England and Wales took effect on 1 April 2002
Building (Procedures) (Scotland) Regulation 22 - Part J , 6th Amendment took effect on 6 March 2002 (subsequently renamed Part 6)
Building Regulations NI - Part F in Northern Ireland


Titles (England & Wales) :
The Building Regulations 2000
Approved document L1 Conservation of fuel and power in dwellings 2002 Edition

The Building Regulations 2000
Approved document L2 Conservation of fuel and power in buildings other than dwellings 2002 Edition

The documents give guidance, approved by the Secretary of State, on complying with Building Regulations Schedule 1 and regulation 7, in England and Wales


Key items covered in Part L1 and J:

1. Standard of building insulation

2. Thermal standards for glazing

3. Standards for air tightness and limiting thermal bridging
In L1, designers must either work to an associated DTLR/DEFRA publication ‘Limiting thermal bridging and air leakage: robust construction details, or submit additional calculations demonstrating equivalence.

4. Heating requirements include boiler efficiency. In Scotland, 7 day timers must be fitted.

5. Lighting efficiency requirements

6. Standards for overall heating and hot water system performance, including boiler seasonal efficiency. The elemental method includes boiler efficiency

7. Standards for inspection and commissioning

8. Guidance for operational information for householders

9. Regulations to cover refurbishment/retrofitting in existing buildings and replacement of glazing, boilers, and hot water vessels

10. Methods of calculating U values, to European standards.

11. Conservatories attached to existing dwellings are included

Dwellings can comply with Part L1 or J under one of three criteria:

1. Elemental method
2. Target U value method
3. Carbon Index Method

In addition, the SAP rating must be calculated and notified to building control and posted as a notice in a new dwelling.

I carry out a combined calculation that deals with all these as well as U values. In this way I can determine the effect of any change in order to achieve compliance at optimum cost. At the same time I can determine carbon emission (which is relevant to an EcoHomes rating), and the running cost.

Refurbishments, conversions and extensions - I advise all clients to agree with the Building Control officer the extent of application of the regulations L1 or J at an early stage in the design.

ELEMENTAL METHOD

Element Maximum U-value (W/mk)

Pitched roof with insulation between rafters 0.2
Pitched roof with integral insulation 0.25
Pitched roof with insulation between joists 0.16
Flat roof 0.25
Wall 0.35 (0.30 in Scotland)
Floor 0.25
Windows, doors and rooflights – metal frames 2.2
Windows, doors and rooflights – wood or pvc 2.0

Boiler - minimum SEDBUK efficiency (England & Wales)
Gas 78%
LPG 80%
Oil 85%
Electric – - use Target U value or Carbon Index method
In Scotland poorer efficiencies and electric heating can be applied to the Elemental method, but the above U values are replaced by lower more onerous figures.


TARGET U-VALUE METHOD

This takes account of the boiler efficiency and solar gain through South facing windows as well as the heat loss through the exposed elements.

The average U value has to be better than a Target U-value, which is calculated for the building by a formula involving exposed roof area, total area of exposed elements, ground floor area, total floor area, boiler SEDBUK efficiency, and proportion of South facing windows.

Although the calculation is more complex, it is often easier to comply via the Target U value than via the Elemental Method.


CARBON INDEX METHOD

The Carbon Index is a measure of the carbon emitted to the atmosphere from the heating and hot water fuel per square metre of floor area in a year, on a log scale of 0 (worse) to 10 (best).
Compliance can be achieved by designing for a Carbon Index 8 or higher.
This allows still more flexibility, within limits, in the U values and glazing areas.


Standard Assessement Procedure (SAP)
Both Part L1 and Part J require the standard assessment procedure to be used to determine the Carbon Index. The standard assessment procedure includes a methodology for handling U values, for instance in relation to walls adjacent unheated areas, and other matters that affect the Elemental and the Target U value.

The SAP energy rating is a measure of the heating and hot water yearly cost for the dwelling, stated in a scale of 0 (worse) to 120 (best). The theoretical yearly cost is derived in the calculation and stated in my report summary. Building Regulations require the SAP rating to be displayed on new premisess, (the SAP certificate) but no particular figure has to be achieved.

Sap ratings can be calculated by means of the standard calculation sheet published by BRE. The procedure involves collecting statistics on a dwelling's size, ventilation, U-values, heating systems, hot water system, and solar heat gain, then performing a calculation on this data to create a rating between 0 and 100. This rating is based on the fuel cost of heating the dwelling, its hot water, and running any necessary pumps and fans. Building Control Authority is empowered to satisfy itself that the person analysing the building is competent to do so. It is obliged to check the mechanics of the calculation, and it may reject any rating if it does not believe the data used within that calculation has been provided competently. Approved Document L/J advises applicants to check with the Building Control to confirm it is satisfied with competency before committing themselves to any rating.

Use of SAP ratings
Housing Associations will usually ask for a particular SAP Rating to be achieved by a design. A SAP Rating always has to be provided to the Local Authority when a dwelling is completed.

The SAP calculation follows the BREDEM model of the Building Research Establishment. NHER ratings (National Home Energy Rating) are similar but include lighting and appliances energy based on the BREDEM 12 model. NHER ratings are not required by Building Regulations.

The EcoHomes environmental assessment incorporates the SAP carbon emission plus energy from lighting and appliances.


U VALUES

 U-values for the wall and roof elements have to be calculated under the combined method to BS EN ISO 6946:1997 as required by Part L1. My procedure inserts the calculated U-value into the calculation for Elemental, Target U value or Carbon Index method. In this way I can test changes to the construction to achieve the optimum results for overall compliance.


WALLS

The internal fixings detailed for combined elements such as precast concrete panel, cavity, insulation and inner surface are allowed for within the ISO 6946 method.

If there are extended metal supports or framing it is necessary to carry out more complex calculations to BS EN ISO 10211-1:1996 and BS ISO 10211-2:2002.

Air gaps in the insulation are also allowed for under BS EN ISO 6946


GLAZING

Different glazing U values can be tried in the calculation, to achieve optimum results.

The U values used for the glazing can be taken from Table 6b of SAP 2001. The regulations give an advantage to metal frames (with thermal break) to allow for the extra solar gain because of the slimmer frames.

It is important that the glazing U value has to apply to the whole glazed unit including the frame. The centre pane U value alone is not applicable.

The calculation of glazing U value can be subject of a separate study or can be the work of the glazing supplier.

To put current UK standards this in perspective, with U-values of 2.2, glazing with U = 1.9 is standard in Norway,Sweden,Denmark and Austria. These countries are planning to move to values in 1.1 to 1.4 range.


THERMAL BRIDGING AND AIR LEAKAGE


These two topics are taken together because under Part L1, if the design uses "Limiting thermal bridging and air leakage: robust construction details", published alongside the Approved documents, then no further assessment to judge compliance is needed. It is simplest for the architect to base the design on the robust construction details.
If this is not the case detailed calculations have to be carried out for each case, such as lintels, jambs, sills etc. The details are based on more usual domestic constructions and have to be interpreted for the curtain wall and precast situation, but in principal the avoidance of thermal bridging in the details relies on continuing the surrounding insulation in wall etc past the lintel or jamb etc without reducing its thickness.

Air leakage limitation is more difficult to demonstrate through the standard details because of the difference in construction. The alternative approach allowed in Part L1 is to pressure test the building.

Building Regulations require that any U-value calculation takes into account the effect of significant cold-bridges in the construction of the dwelling. Therefore the U-value of a loft insulated between the joists must be proportionally adjusted for the increased heat lost through the joists where there is no insulation; and the U-value of a wall using thermal blocks must be adjusted for the heat lost through the mortar joints.

Other isolated cold-bridges must be avoided, e.g. at window reveals where any frame should significantly overlap an insulator, and a continuous steel lintel should have at least 15mm of lightweight plaster coating the inside.


HEATING and AIR CONDITIONING

Boilers: If the boiler has a SEDBUK rated efficiency, this is used in the Target –U value and Carbon Index. If not, Building Regulations default efficiencies are inserted in the calculation.

Approved document L1 makes no stipulations about use of air conditioning. This is because of it’s rarity in UK dwellings. The use of electricity for heating prevents the dwelling from complying under the elemental method. The use of an air to air heat pump allows the equivalent efficiency of 250% to be used in the target U value and carbon index calculation in these calculations, which offsets the high carbon cost of electricity production and opens a route to compliance for all electric buildings.

Heat pumps operate by using electricity to move energy from the ground, a water source or the air, which effectively gears the electricity consumption so the effective efficiency is 250% to 320%.


Target U-values can be improved further by changing from air-to-air to ground or water source heat pumps, with higher efficiencies of 300 and 320%. The feasibility of this would depend on site conditions. Ground source heat pumps can be expensive. Water source heat pumps can be used when there is a suitable source, such as a river or canal, nearby. The air source system is likely to be lowest in capital cost.

Changing to central combined heat and power plant improves the carbon index.


CONTROLS

The use of more efficient heating controls is reflected in the carbon index.


WATER HEATING

Improvement to water heating would improve the carbon index, but have no effect on the target U value.

The carbon emission from electric water heating often exceeds that from heating.

It would be possible to improve on this considerably by using a ground or water source heat pump to preheat the hot water, or through the addition of solar water heating. This would improve the carbon index, but has no effect on the target U value.


UK DOMESTIC ENERGY COSTS
3 BED HOUSE DETACHED HOUSE YEARLY HEATING COST
This table was calculated using the Building Regulations SAP worksheet for a typical new dwelling but with current actual fuel costs substituted for the standard DEFRA costs.
Nov-2001

GAS, standard boiler.......................................... £325 Pounds
GAS, condensing boiler ......................................£258
OIL, standard boiler.............................................. £285
OIL, condensing boiler......................................... £237
LPG, standard boiler............................................. £564
ELECTRIC storage heaters, auto controls............... £500
ELECTRIC DAY RATE heaters, appliance controls. £756






return to notes top

HOME







BUILDING REGULATIONS 2002
BUILDING REGULATIONS - ENERGY EFFICIENCY PROVISIONS
DOMESTIC BUILDINGS - Part L1/ J - achieving compliance
NON DOMESTIC BUILDINGS - Part L2 - achieving compliance

DWELLINGS - (PART L1)

KCE provide a full service in designing to comply with the energy efficiency provisions and in certifying compliance

For a detailed description of the domestic buildings Part L1 regulations and the KCE service, click here or phone Stephen Kinsella, 01934 838624 or email sjkinsella!AT!ee.org (anti-spam - please replace !AT! with @ ).


-->A BRIEF SUMMARY of PART L1 / J:
Dwellings have to comply with regulations under any one of three methods:

The traditional approach, based on U values of elements, modified according to heating system efficiency

This method enables more efficient heating systems to offset the U-value requirements. Can enable less onerous U-values.

This is calculated through the Standard Assessment Procedure, but unlike the SAP rating, is independent of fuel costs. As with the SAP rating, the carbon index takes into account all the design factors affecting energy use, including size, shape and orientation. Through suitable design it is possible to comply under the carbon index criterion when compliance is not achieved under the other methods, giving the most flexibility to the designer.
The SAP RATING must be calculated and displayed in the new dwelling on completion.


NON - DOMESTIC BUILDINGS - (PART L2)

For assessment of your building design for Building Regulations L2 compliance, send the drawings to Stephen Kinsella, KCE Energy and Environment, The Old Forge, Kingston Bridge, Clevedon, Somerset, BS21 6TX. Phone me on 01934 838624 or email sjkinsella!AT!ee.org (anti-spam - please replace !AT! with @ ).

I carry out integrated calculation of all three methods of compliance and provide you with:

1. A report on the optimum means of complying with part L2
2. Carbon emissions achieved
3. Certificate of L2 compliance.

 I will first advise you of the cost of the assessment and will agree the programme with you. Payment must be made before the start of the assessement.



A BRIEF SUMMARY of PART L2:

A. DESIGN compliance is achievable via one of 3 routes:

A1. Elemental method
Or A2. Whole Building method (for offices, schools and hospitals only)
Or A3. Carbon Emissions method

B. CONSTRUCTION compliance takes into account:
Thermal bridging methods or thermographic survey (buildings over 1000 m2 ).
Airtightness (Pressurisation test for buildings over 1000 m 2).
Commissioning report.

C. INFORMATION compliance takes into account:
Log Book.
Metering Strategy.
Calculation of carbon emissions (for offices over 200 m 2 ).

DESIGN

1. The Elemental Method takes into account these factors in the design:

1. U values
2. Thermal bridging
3. Opening areas
4. Air leakage
5. Solar overheating
6. Carbon intensity of heat generating equipment
7. Heating controls
8. Hot water controls
9. Insulation of pipes and vessels
10. Lighting methods (shop displays are exempt)
11. Lighting controls
12 Air conditioning and mechanical ventilation systems

2. The WholeBuildingmethodof design for offices takes into account:
1. Whole office carbon performance rating
2. Air leakage
3. U values

For Schools and Hospitals the design must comply with relevant DfEE/ NHS guides.

3. The Carbon Emissions Method of design takes into account calculation of:
1. Carbon emissions of a 'reference building' designed to the Elemental Method

2. Carbon emissions of the proposed building

Thus the Carbon Emissions Method needs full consideration of the Elemental Method, then allows adjustment (within limits), enabling considerable freedom of design.

Buildings need to be designed under the Carbon Emissions method rather than the traditional elemental or target U value method in order to reflect all the benefits of energy efficient design.
KCE provide a full service in designing to comply with the energy efficiency provisions and in certifying compliance.
Revised 6 December 04
KCE home page