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Part L Energy Conservation

1. Introduction

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Section 1 - Introduction

Part L of the Building Regulations is concerned with the conservation of fuel and energy in dwellings. Part L for dwellings, is supported by a Technical Guidance Document (TGD) L Dwellings 2019 which gives guidance on how to satisfy the energy performance provisions of the Building Regulations for new and existing dwellings.

The TGD quotes the regulatory requirements where relevant for the sake of completeness. These provisions are distinguished in the text by a grey background. In cases of doubt, however, it may be necessary to refer directly to the Building Regulations as amended.

The TGD was published in 2019 in support of the amendments to the Building Regulations, Statutory Instrument ( S.I. No. 292 of 2019) and in support of the application of the European Union (Energy Performance of Buildings) Regulations 2019 (S.I. No 183 of 2019). Both S.I. came into force on 1st November 2019.

This guide covers conventional means of providing primary and secondary space heating and domestic hot water for dwellings in Ireland. This guide is the supporting document referred to in Building Regulations TGD L & Energy Performance of Buildings Regulations 2019 Dwellings Par 1.4.2.4 as a source of guidance on the means of complying with the requirements of the Building Regulations for space heating systems and hot water systems. The guide was prepared in consultation with relevant industry bodies.

The co-operation of the UK authorities (Department of Communities and Local Government) is gratefully acknowledged in allowing the use of the information in its publication “Domestic Heating Compliance Guide” for official use in Ireland.

For new dwelling requirements in Part L of the Building Regulations 2019, guidance is provided on the design limits for building services systems referred to in Section 1 of Building Regulations 2019 TGD L- Dwellings. For existing dwellings, guidance is provided on reasonable provision for the installation or replacement of controlled services as referred to in Section 2 of Building Regulations 2019 TGD L-Dwellings.

This supporting document identifies standards of provision that meet the guidance for systems in new build and in those in existing buildings when work is being undertaken. The levels of performance for new and existing dwellings differ only where practical constraints arise in existing dwellings while it is recognized that the guide covers a range of frequently occurring situations but alternative means of achieving compliance may be possible. The status of alternative provisions is explained in the ‘The Guidance’ section at the front of the Technical Guidance Documents.

This guide also references publications which include information on good practice for design and installation over and above the minimum regulatory provision.

1.1 How to use this guide

This guide covers compliance with the requirements of the Building Regulations 2019 Part L for conventional space heating systems and hot water service systems in dwellings.

The guide comprises four self-contained fuel-based sections, and five specialist technology- specific sections. Each fuel-based section addresses all the requirements applicable to primary and secondary space heating and hot water service technologies for the particular fuel. The specialist technology-specific sections provide further guidance on the minimum provisions for particular specialised space heating and hot water service technologies. The structure of the guide is as follows:

Fuel-based sections:

  • Section 2 Gas-fired primary and secondary space heating and hot water service

  • Section 3 Oil-fired primary and secondary space heating and hot water service

  • Section 4 Electric primary and secondary space heating and hot water service

  • Section 5 Solid-fuel primary and secondary space heating and hot water service

Specialist technology-specific sections:

  • Section 6 Community heating

  • Section 7 Underfloor heating

  • Section 8 Heat pumps

  • Section 9 Solar water heating

  • Section 10 Micro-CHP (Combined Heat and Power)

For any particular application, the relevant fuel-based section and/or specialist technology-specific section must be read in conjunction with all elements of this introduction section:

    1. Introduction
  • 1.1 How to use this guide

  • 1.2 Glossary

  • 1.3 The Building Regulations 2019 requirements and the guidance in Technical Guidance Document L – Dwellings 2019

  • 1.4 Replacement of primary heating appliances

For each type of space heating or hot water service system, guidance on the minimum provisions needed to comply with Part L is supported by commentaries. They are in italic font with a shaded background and are labelled ‘Supplementary information’. They are useful when interpreting the minimum provisions and, in some cases, provide links to best practice guidance. They do not specify minimum provisions.

1.2 Glossary

Technical Guidance Document L (TGD L)

Section 1 of TGD L Dwellings 2008 gives guidance on how to satisfy the Building Regulations energy efficiency requirements when building new dwellings. Effective from 1st July 2008.

Section 2 of TGD L Dwellings 2008 gives guidance on how to satisfy the Building Regulations energy efficiency requirements when carrying out work in existing dwellings. Effective from 1st July 2008.

The Building Regulations

S.I. No. 497 of 1997 as amended by the Building Regulations (Part L Amendment) Regulations (S.I. No. 259 of 2008) ensure the health, safety, welfare and convenience of people in and around buildings and reasonable provision for the conservation of fuel and power and access to and use of buildings by providing functional requirements for building design and construction.

Minimum provision

In this document ‘minimum provision’ refers to the provisions needed to demonstrate compliance of space heating and hot water service systems installed in dwellings with the Building Regulations 2008 energy efficiency requirements.

Supplementary information

The commentaries labelled ‘Supplementary information’ may be useful when interpreting the minimum provisions and, in some cases, provide links to best practice guidance.

DEAP

An acronym for Dwellings Environmental Assessment Procedure, which is the national methodology for calculating the energy rating of dwellings

1.3 The 2008 Building Regulations requirements

Guidance in TGD L Dwellings 2019, Sections 1 and 2

The Building Regulations relevant to the Conservation of Fuel and Energy in Dwellings are repeated for easy reference at the front of TGD L Dwellings 2019 in the ‘Guidance Section’, which can be viewed on https://www.housing.gov.ie/.

For new dwellings the provision of heating and hot water services systems has to be considered as part of the overall design of the building. For heating and hot water services systems works in existing dwellings provision can be considered in isolation. Both sections of the TGD L Dwellings 2019 refer to this publication as the source of detailed guidance on reasonable provision.

1.4 Replacement of primary heating appliances

In order to comply with these requirements, replacement appliances providing primary space heating and/or hot water in existing dwellings should meet the following conditions:

  • Oil or gas boilers installed as replacements in existing dwellings should have a minimum seasonal efficiency of 90%, where practicable.

  • For fully pumped hot water-based central heating systems utilising heat pumps, the seasonal space heating energy efficiency should not be less than the minimum requirement in accordance with Ecodesign regulations.

  • Replacement storage heaters should have a heat retention not less than 45% measured according to I.S. EN 60531:2000.

  • For fully pumped hot water-based central heating systems utilising a biomass independent boiler, the boiler seasonal efficiency should be not less than 77% as specified in the DEAP manual and the associated HARP database maintained by SEAI (www.seai.ie/harp).

Space heating systems should be effectively controlled so as to ensure the efficient use of energy by limiting the provision of heat energy use to that required to satisfy user requirements, insofar as is reasonably practicable. The aim should be to provide the following minimum level of control:

  • Automatic control of space heating on the basis of room
    temperature, e.g. room thermostat, thermostatic radiator valves;

  • Separate and independent automatic time control of space heating and hot water, and

  • Shut down of boiler or other heat source when there is no demand for space (or water) heating from that source, e.g. boiler interlock.

Controls for replacement heat pumps should be the same as for new heat pumps.

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