• Home
  • Heating & Boilers
    • Air Source Heat Pumps
    • Air Source Heat Pump Running Costs Calculator
    • Gas Boiler Replacement
    • Replacement Boiler Cost Online Calculator
    • A guide to gas boiler replacement costs
    • Making The Best Of Your Boiler Warranty
    • Wood Burning Stoves
    • Boiler Flues
    • Heating Suppliers
      • Baxi Gas Boilers
      • Glow-worm Gas Boilers
      • Ideal Gas Boilers
      • Potterton Gas Boilers
      • Vaillant Gas Boilers
      • Worcester-Bosch Gas Boilers
  • Roofing
    • A Guide To Roof Construction
    • Pitched roof problems
      • Overview
      • Slipped Tiles & Slates
      • Replacing Ridge Tiles
      • Roof Valleys Leaking
      • Rebedding Roof Verges
      • Dealing With Moss
      • Repointing Chimneys
      • Replacing Guttering
      • Repairing Roof Felt
      • Condensation In Roofs
      • Repairing Torching
      • Replacing A Pitched Roof
    • Replacing Guttering
    • Safe Working
    • Choosing A Roofing Company
    • Loft Conversions
  • Energy Saving
    • Average Energy Consumption Calculator – England & Wales
    • Average Energy Consumption Calculator – Scotland
    • Average Energy Consumption In The Home – How Do You Compare?
    • Energy Efficient Homes: Eco Houses, Zero Carbon Homes, Passivhaus & EnerPHit
    • Mechanical Ventilation Heat Recovery Systems (MVHR) Explained
    • Radiator Sizing Guide And BTU Calculator
  • Green Home Grants
    • Floor Insulation
      • Using Robotics for Underfloor Insulation of Suspended Timber Floors
    • DIY Floor Insulation
      • Underfloor Insulation Of Suspended Timber Floors
      • Insulating A Suspended Timber Floor From Above Floor
      • Insulating A Suspended Timber Floor From Underneath The Floor
  • Battery Storage & Solar
    • Solar PV Panels
    • Solar PV Panel Payback And Costs In 2019
    • Solar Panel & Battery Storage Calculator
    • Solar PV Panels: Example
    • Solar Water Heating Panels
    • Solar Battery Calculator: Likely Bill Savings
  • Other
    • Blog
    • News
    • Rainwater Harvesting Systems
    • Types Of Shower: The Best Shower For You
    • Fitting An Electric Shower

Great Home

Independent Advice On Improving Your Home

Building Regulations: Current U-values for Insulation in Homes

October 12, 2020 by Jon Davies 5 Comments

As there are a number of figures thrown around, relating to U-values in new homes or extensions it is worth a reminded of some of the figures used in current Building Regulations.

Building Regulations L1A Conservation of fuel and power v2

Building Regulations Overview

The Building Regulations cover all aspects of building a dwelling, including fabric heat loss and air permeability. They are periodically reviewed to upgrade standards, with a major overhaul every decade. Insulation standards were first introduced in the 1970s, with the standards of required energy performance dramatically increasing over the last 50 years. Building Regulations determine the energy performance of both new homes and any extensions to existing homes, which are covered in two documents:

  • Part L1A, Conservation of fuel and power in new dwellings
  • Part L1B, Conservation of fuel and power in existing dwellings

The current regulations are the 2010 Building Regulations, incorporating amendments in 2013 and 2016. The regulations allow some freedom for building designers to chose how to achieve the overall energy performance level.
Example: A design could chose to have better levels of insulation for the floors and less for the walls as long as that achieved the standard of performance required.

For new build homes, there are two levels for a designer to consider:

  • Limiting Fabric Parameters: The minimum requirements for an individual building element. However if minimum standards were used throughout then the home would fail the overall TER (Target CO2 Emissions Rate).
  • Concurrent Notional Dwelling Specification: A set of requirements for all building elements which together should meet the overall standard (the TER).
AreaLimiting Fabric
Requirement

W/(m2K) unless stated
Concurrent Notional
Dwelling Specification
W/(m2K) unless stated
Roof0.20.13
Wall0.30.18
Floor0.250.13
Windows2.01.4
Doors2.01.0 – 1.4 depending on glazing
Air permeability10 m3/(h.m2) at 50 Pa10 m3/(h.m2) at 50 Pa
2010 Building Regulations Part L1A new dwellings

In general, if a specification below that of the Notional Dwelling Specification is used, then this should set alarm bells ringing, as the shortfall would need to be addressed by a higher specification elsewhere.

Extensions

For extensions, then it is considered unreasonable to ask a dwelling owner to knock down and replace existing walls, although they can be asked to upgrade them. So the focus is on new thermal elements and the standards for these are:

AreaNew Thermal Element
W/(m2K) unless stated
Wall0.28
Roof0.16 – 0.18 depending on pitch
Floors0.22
Windows & DoorsAs part L1A
Air permeabilityNo specific requirement as this is a whole dwelling requirement.
However approved construction details should be used.

Existing thermal elements should be upgraded to an improved standard if they exceed a u-value of 0.7 for walls/floors or 0.35 for roofs. The improved u-value required is:

AreaImproved U-value
W/(m2K) unless stated
Wall-cavity insulation0.55
Wall – external or internal insulation0.30
Floor0.25
Roof0.16- 0.18
depending on roof pitch

Filed Under: Energy Use, Green Home Grant, Insulating Your Home, Reducing Energy Bills, Roofing

Comments

  1. Julian says

    December 7, 2021 at 6:49 pm

    Do these figures apply to existing buildings being converted from say Industrial to a Dwelling or a Barn to a Dwelling? Looking at the materials used, I struggle to believe many of the conversions we see on the TV shows could possibly meet these figures. The W/(m2K) values are difficult to achieve with retrofit insulation unless the depth is really high.

    Reply
  2. Mark Searle says

    October 19, 2021 at 8:49 am

    Ventilation is a key issue in how a house perfoms. Opening a window is clearly not the way forward in a cold winter if we want to save the planet!
    To achieve adequate insulation and thermal preformance and a healthy environment a ventilation system has to be part of the mix. So that you do not lose heat with your stale air, a heat recovery ventilation system is the way forward.
    Not difficut in a new build but a tricky retrofit.
    The payoff is that it captures up to 95%+ of the heat you would normally lose. So all that heat from a shower or cooking is effectively recycled without the moisture.
    For a retrofit, each house is different, but if you are insulating internally because exterior insuation is not an option, then ducting could more easiy be installed at the same time.
    It is best to have a whole house plan even if you can only carry out one aspect at a time. That way you are not having to go back over new work. e.g. fit internal insulation and ductwork for a heat recovery ventilation sytem even if the actual ventilation unit is fitted later.

    Reply
  3. Katy Hollway says

    April 23, 2021 at 3:21 pm

    Hi!
    Our new build house has been built with a u-value of 0.19 for the roof. It was designed and built with rooms in the roof. Looking at your table, it seems like it should be different. The new build company are saying that it is within building regulations. Is it? What should it be?

    Reply
    • Jon Davies says

      April 26, 2021 at 4:16 pm

      Hi Katy,

      When designing a house, two factors have to be taken into consideration. The first is the minimum standard of individual components (limiting fabric parameters). For the roof component this would be 0.2 and your roof u-value is within this. The second factor is the notional Concurrent Notional Dwelling Specification. This is an example mix of components that together ensure the house would meet the building regulations overall. It allows the designer to achieve the same overall energy performance result in different ways rather than specifying only one way of doing something. In your case the 0.19 u-value of the roof component would be compensated for by better values elsewhere (such as the walls, windows or doors).

      Hope this clarifies
      Kind regards
      Jon

      Reply
  4. Keith Brannan says

    November 9, 2020 at 11:29 am

    Interesting article on the complexities of thermal control in new housing identifying the considerable difference in performance required by the “Fabric limiting requirement” and the “Concurrent notional dwelling specification”- Central government needs to clarify these design parameters and take account of heat loss and gain from construction techniques that have inadequate natural ventilation provision for healthy living-
    High levels of Covid19 transmission in confined poorly ventilated living conditions is highlighting this concern!!
    I remember a quote from a traditional builder years ago saying “open the window and put another log on the fire” !

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Show you are a real person * Time limit is exhausted. Please reload CAPTCHA.

Welcome

Jon Davies

Hi I'm Jon. This website seeks to help those searching for the basics about improving their home. It offers an independent view, trying to balance the interests of … read more

Recent Posts

  • £450 Million Boiler Upgrade Scheme Announced By Government
  • Green Home Grant Voucher Scheme Closes 31 March 2021
  • Hydrogen Heating Gets Boost In Government Green Industrial Revolution
  • Building Regulations: Current U-values for Insulation in Homes
  • Green Home Grant Voucher Scheme Live 30 September 2020

Tweets by Greathome1

* Cookie & Privacy Policy * Website Terms of Use * Contact Us
Copyright © 2022 Great Home