March 2020

Building Regulations
THE A,B,C’S OF PART L AND PART F
Jonathan Ducker, Head of Regulatory Affairs at Kingspan
Insulation UK, explains what’s going on with Part L and
Part F...
If you’ve been keeping an eye on recent
industry news, you may have noticed a few
signs that the Government is starting to get
serious about meeting its net-zero greenhouse
gas emissions target by 2050. Over the past
couple of months consultations on tightening the
requirements within Part L and Part F of the
Building Regulations for new homes in England
and Wales closed, with new versions of the
Approved Documents set to come into force later
in the year.
But what exactly are these documents and how is
it likely to affect your work?
What is Part L?
Part L of the Building Regulations sets out the
mandatory requirements for the conservation of
fuel and power. Approved Document L (ADL) is
not mandatory, but it provides guidance on how to
meet those requirements, including overall
emissions targets and specific limitations such
as worst case U-values. The Building Regulations
themselves are devolved with separate
requirements in England, Wales, Scotland and
Northern Ireland.
clear limits on the expected heat demand for the
building, based on the thermal efficiency of the
building envelope. This has been scrapped in the
consultation and whilst the notional building for
option 1 (which is used to generate the overall
target emissions rate) has an external wall U-
value of 0.15 W/m²K, the actual minimum backstop
is far weaker, at 0.26 W/m²K. This is much
worse than even the existing Welsh and Scottish
equivalents.
In theory, this approach in combination with the
way that the newly introduced Primary Energy
metric is calculated, could allow homes to be
built using all the backstops for fabric elements,
leading to higher heating demand than at present,
providing this is compensated for with lots of
photovoltaic (PV) generation. This high
consumption approach is short-sighted and is
ultimately likely to mean that the envelope
performance of these buildings will have to be
“It makes sense to use
this year’s revisions as
an opportunity to gear
up and begin to
implement solutions
which can provide an
improved fabric
performance, that sets
those buildings up for
the future”
extensively upgraded in the future to allow them
to realistically reach net-zero emissions.
What are the recommendations in the
Welsh Consultation?
The Welsh approach, in contrast, seems more well
considered. They again offer two uplift options, but
the targets set are more ambitious: 37% (preferred)
and 56%. Detailing requirements are again
tightened and whilst FEES were never adopted
within the Welsh Part L, they instead set much
tighter fabric backstops as you can see below:
What are the recommendations in the
English consultation?
The consultation gives two uplift options designed
to achieve a 20% and 31% (preferred) reduction
on current emission levels. Whilst these top-line
figures sound substantial and greater emphasis
has been placed on detailing and addressing
thermal bridging, the approaches outlined are
questionable, particularly when it comes to the
building fabric.
The current version of ADL incudes a Fabric
Energy Efficiency Standard (FEES) which sets
“The new versions of ADL for housing are expected
to be implemented before the end of the year”
60 TC MARCH 2020