Windows
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When assessing window area consider the whole dwelling (windows, glazed doors
and roof lights), including any extensions (but not conservatories).
Typical applies if the surface area of the glazing in the dwelling is essentially as
would be expected of a typical property of that age, type, size and character. Even if
there is slightly more or less glazing than would be expected, up to 10% more or
less.
More than typical applies if there is significantly more surface area of glazing than
would be expected (15%-30% more), perhaps because there is a large sun room or
numerous patio doors have been added.
Less than typical applies if there is significantly less glazing than would be
expected. This is rare as homeowners tend not to take out windows, but a property
may have an unusual design with few windows.
Much more than typical and Much less than typical should be used for those
dwellings with very unusual amounts of glazing; such as a glass walled penthouse
flat or a Huff Haus. Due to this option allowing measurements of each window to be
accounted for, it can also be used if a dwelling has a mixture of glazing types e.g.
single, double and triple.
Window U-values and g-values
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U-values and g-values for windows can
be overwritten only if documentary
evidence is provided, which can be
either a Window Energy Rating
certificate (as defined by BFRC) or
manufacturer’s data. The U-value is for
whole window, not centre pane.
Use Table S14
Appendix S - Doors
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In RdSAP the definition of what is a window and
what is a door is defined by the area of glazing in
relation to the area of the whole opening, i.e. door
and frame. To be classed as a window a glazed
door and frame must contain glazing amounting to
60% or more or its surface area.
An external door is a door that forms part of the
heat loss perimeter of the dwelling. A door to a
heated access corridor is not included in the door
count.
External Doors
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A door is counted as insulated only if
documentary evidence is provided, which
must include U-value or
manufacturer reference enabling the assessor
to ascertain the U-value from the
manufacturer.
If there is more than one insulated door and
they have different U-values, enter the
average U-value.
Draft proofing
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RDSAP 9.91 requires the DEA to assess and
collect the number of windows and doors
that are draught proofed to allow a more
accurate recommendation for draught
proofing.
Look for draught strip around doors and
windows. With multiple glazed windows
open the windows and check the seals.
Draught proofing
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All external doors and at least 2 windows per
building part should be examined.
If a window is locked or inaccessible then endeavour
to check another one.
If the state of the draught proofing cannot be
determined then take triple, double or secondary
glazed as being draught proofed, and single glazed
windows and doors as not draught stripped.
Include glazing in a non-separated conservatory.
The percentage draught proofed is [(number of
draught proofed windows & doors) divided by (total
number of windows & doors)] x 100
External Doors
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A door is counted as insulated only if
documentary evidence is provided,
which must include U-value or
manufacturer reference enabling the
assessor to ascertain the U-value from
the manufacturer.
If there is more than one insulated door
and they have different U-values, enter
the average U-value.
Standard Assessment
Procedure
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Full SAP is used in Building Regulations, and has to
be calculated for every new home built, for new
extensions and conversions
Introduction of RDSAP
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The RDSAP (Reduced Data SAP Rating) has been
developed to provide a consistent method for
existing houses
Reduced Data set than Full SAP standardised methodology for
energy rating existing properties
Assumptions
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Assumes
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standard occupancy
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standard heating pattern
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lighting
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Locality
Running costs calculated using a standard (average) heating pattern of
9hours heating a day during the week and 16 hours a day at the
weekend
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Living area heated to 21°C and the rest of the house to 18°C
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Excludes (factors that do not affect RdSAP conventions)
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cost of cooking
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running other appliances
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Rating is not affected by living habits of the occupying households
RdSAP changes
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Appendix S – Main guidance of criteria for survey
techniques
Appendix T – Improvement Measures guidance
Conventions – this is to standardise, provide
consistency and ensure DEAs are compliant. They
are developed by the stakeholder group and
formally released by CLG (formerly DCLG)
New changes highlighted in blue for 2012
Draught proofing is a cheap and
efficient method of saving both
energy and money
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Draughts are similar to ventilation in that they supply the
home with fresh air. However, draughts are uncontrolled and
can let in too much cold air as well as allowing heat to
escape.
Draught proofing blocks up any unwanted gaps that let cold
air in
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Types of draught proofing can include:
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– Self adhesive sealant strips
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– Brushes
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– Spray foams (sprayed into gaps around windows)
Habitable rooms
This is a simple count of the number of habitable rooms in the dwelling
Habitable rooms include living room, sitting room, dining room, bedroom, study
and similar;
The count of habitable rooms excludes hall, stairs and landing, kitchen, utility
room, bathroom, cloakroom, en-suite and similar
Where there are ‘open plan’ rooms, count as 1 room. A lounge/dining room with
the door permanently removed (hinge holes filled etc) is one habitable room
In addition to the above, if half or more of the habitable rooms are not heated
these rooms should be recorded on the survey form (for inadequate heating
purposes).
For a kitchen to be a kitchen/diner it must have space for a table and 4 chairs
A lounge/dining room where the door was temporarily removed (ie architrave
and hinges still there) is two habitable rooms
An non-separated conservatory adds to the habitable room count if it has an
internal quality door between it and the dwelling.
Some important definitions
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Heat Loss Wall – is one which separates the heated part
of the dwelling from the unheated external environment
or a part of the dwelling which is unheated i.e. a wall
through which heat will be lost
Party Wall – is a shared wall between two properties
which may be semi-detached, terraced or flats
Party walls are not considered heat loss walls as losses
or gains through party walls to other dwellings (or
premises that are normally expected to be heated) are
assumed to be zero.
Measuring buildings
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A lot of the data required from inspection relates to
measurement of floor areas.
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RICS Code of Measuring Practice
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Gross Internal Area (GIA)
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“Gross Internal Area is the area of a building measured to the
internal face of the perimeter walls at each floor level.”
Party walls in shared ownership are to be measured to their
centre line
Excludes perimeter wall thickness and external projections
So what do we actually have
to measure?
Floor Dimensions –
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Measure between the inner surfaces of the external or party walls,
disregarding the presence of any internal walls
Alternatively, the external walls of the building can be measured
and used instead; the software then converts these figures, making
an allowance for the thickness of the walls
When entering measurement data, you are required to indicate
which measurements are being used – internal or external.
Stairs - the floor area should be measured as if there were no stairs
but a floor in their place at each level.
Built-in Cupboards should be included in the calculation of the floor
area where these are directly accessible from the occupied area of
the dwelling.
A SET OF 6 FLATS SEPARATED BY
A ‘HEATED’ ACCESS CORRIDOR.
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Flat A is an Enclosed End-Terrace flat that has two heat loss walls, 5+4 =
9m. The access corridor is heated and the wall between the flat and
corridor is deemed to be a party wall and as such no heat loss is
calculated through it.
A SET OF 6 FLATS SEPARATED BY A
‘HEATED’ ACCESS CORRIDOR.
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Flat B is an Enclosed Mid-Terrace flat, and has just one heat loss
wall measuring 4m.
Example 5
This set of 6 flats is separated by an ‘unheated’
access corridor.
Flat A is an Enclosed End-Terrace
flat that has three heat loss walls,
4+5+4 = 13m.
Flat B is an Enclosed Mid-Terrace
flat, and has two heat loss walls,
4+4 = 8m.
Floor type considerations
Suspended Timber and suspended Concrete – look for air bricks at the
lower levels of the property
Solid – there is no air brick and the floor has not steps towards the
entrance of the property
You must also indicate what is on the other side of the floor such as
Ground floor, Above heated space, same dwelling below etc
Flats and position
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When we deal with a flat, we have to consider the
position it occupies in the block of flats. We do this by
starting from the ground floor, mid-floor and top floor
Bay windows
calculations
How to measure wall
thickness
1. Take a measurement at door or
window reveals
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A difference in wall thickness is not in itself a reason to include an alternative wall, unless it is a stone wall and the
dif-ference in thickness is greater than 100 mm.
Disregard when less than 10% of total exposed wall area of
the building part (including windows and doors) unless
documentary or visual evidence exists of different retrofitted insulation either of the alternative wall or of the remaining wall in the building part.
When entering alternative wall area into the software exclude the area of any windows and doors contained in the
alternative wall.
Consolidate walls of same type.
Walls: Dry-lining
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Dry-lining is the addition of plaster board to an existing wall,
either with dabs of plaster, on battens, or lath and plaster. Drylining is any wall lining with no insulation which creates an air
space behind it. Although dry lining alone is not insulation, it can
reduce the U-value significantly. It may be applied to ‘straighten’
an old uneven wall.
The presence of dry-lining should only be assessed when
insulation is as-built or unknown and for the following wall
constructions:
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Granite or Whinstone
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Sandstone
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Solid brick
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YOU CAN ASSESS DRYLINING BY TAPPING THE
WALL:
Dabs of plaster adhesive will make a different
sound to the rest of the plaster board
Battens will sound solid, the air gaps in between
will sound hollow
Lath and plaster will normally be visible in
cupboards and should produce a hollow sound
when tapped
If you are in doubt, do not select dry-lined.
Internal Wall Lining
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This is a new convention for the new RDSAP 9.91 data
collection ‘dry-lining’ or ‘internal wall lining (creating
an air space behind)’.
This includes any type of internal lining that creates an
airspace behind it, e.g. plasterboard on dabs, lath and
plaster. Use tap test for plaster board on dabs or on
battens. If tap test is inconclusive regard as not drylined.
Note: This applies only to stone or solid brick walls.
Heat loss floor area for
houses and bungalows
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The area of the lowest occupied floor of the main dwelling is a
ground floor. If the lowest occupied floor of any extension is not
a ground floor increase the level of each storey in that building
part by 1 for the purposes of the SAP calculation.
For each building part examine the floor areas on each storey. If
the area of any upper floor is greater than that of the floor
below, the difference in these areas is an exposed or semiexposed floor. This can occur particularly when there is an
integral garage. When external dimensions are being used,
however, the method of dimensional conversion can result in a
small, but spurious, exposed floor area. To avoid that situation.,
the area of exposed floor on any level cannot be greater than the
difference between the area of the current floor and the floor
below measured using external dimensions.
U-value and insulation are mutually exclusive. If U-value is known,
the U-value should be entered and ‘Insulation thickness’ is not
relevant
Stores & utility
rooms
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should be included if they are directly accessible from the
occupied area of the dwelling, whether heated or not
should not be included if they are unheated and
accessible only via a separate external door.
Basements
should be included only if consisting of heated and
habitable rooms.
 Include when accessed via a permanent fixed
staircase such that one is able to walk
downwards facing forwards and either:basement is heated via fixed heat emitters, or basement is open to the rest of the dwelling.
 Does not necessarily contain habitable rooms.
Garages
should be included if heating is provided within the garage from
the main central heating system
should not be included where the garage is thermally separated
from the dwelling and is not heated by the central heating
system.
Attics
should be included if they are habitable rooms, accessed by a
fixed staircase and have natural light
Roof spaces
should not be included unless they are habitable rooms
accessed by a fixed staircase and access to natural light
DETAILED MEASUREMENTS
OF ROOF ROOMS
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Detailed measurements of roof rooms are required only if evidence exists
that the slope, stud wall (or common wall) or gable wall (see Figure S3) have
differing levels of insulation and each of their U values is known. See Figure
S3.
If all elements of the roof room (slope/stud/gable) have the same insulation
and the U-value is available, the U-value can be overwritten whilst leaving the
RdSAP assumed areas as is.
Where detailed measurements are made and the floor area of the parts of the
dormer windows protruding beyond the roof line is less than 20% of the
floor area of the roof room, measure the elements of the roof room as if the
dormers were not there. Otherwise total the vertical elements of all dormers
in that building part and enter as stud wall and the flat ceiling elements as
flat ceiling.
A roof room is indicated as ‘connected’ if it is adjacent to (i.e. at the same
level as) another building part of the same dwelling (which can be either a
roof room or a normal storey).
For detailed measurements of roof rooms there can be up to two of each of:
- flat ceiling
- sloping ceiling
- stud wall (or common wall)
- gable wall
A U-value must be provided for each non-zero area.
Figure S3 : Different parts of roof rooms
Partially insulated
roof rooms
When roof room details are collected, the
following data can be entered:
– Actual area
– Actual U-value
Position of Flats in Block
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When assessing a flat an assessor is now required to record 2
elements for flats;
1. Which floor, 0,1,2,3, etc.? Where the ground/basement level is
recorded as 0,
2. What floor type is the flats lowest occupied floor in the block, as
one of the following options;
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Basement
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Ground-floor
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Mid-floor
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Top-floor
This data is not used in the actual calculation, but it enables the
assessor to control what is written for dwelling type on the EPC.
Heating systems
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What provides space heating?
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Primary heating system
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Heats the largest proportion of a dwelling
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Not normally based on individual room heaters ( for example gas fires in most
rooms) although it can be
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Often provides hot water
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Includes:
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Central heating systems with radiators or underfloor heating
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Community heating
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Electric storage systems
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Electric underfloor heating
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Warm air systems
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Room heaters
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Secondary heating system
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Based on a room heater
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Secondary heating system is to be specified if the main heating system
is not sufficient to heat the dwelling to levels that SAP is based on
These levels are 21°C in living areas and 18°C elsewhere
Gas
Mains gas
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LPG
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Bottled
Electricity
Tariffs
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7-hour off-peak (Economy 7) – typically Dual electric meters
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10-hour off-peak = time for space & water heating
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24-hour = On-peak – typically for single electric meters and key
meters
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Definitions
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Boiler
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Gas or liquid fuelled appliance designed to provide hot water
for space heating
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May or may not provide domestic hot water as well
Condensing boiler
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Designed to make use of the latent heat released by the
condensation of water vapour; boiler allows condensate to
leave heat exchanger in form of condensate
Solar Water Heating