Property Elements. In this section we will look at the different Property Elements and how to identify and assess them. Property Elements. This section of the training will cover a variety of property elements Flats/Maisonette Floor and roof heat loss types Extensions Room in Room
In this section we will look at the different Property Elements and how to identify and assess them.
Technically there is no difference between a flat and a maisonette in RdSAP, the only difference is the description on the 1st page of the EPC. Stroma Certification uses the following definitions for these dwelling types as a guide :
A flat is generally defined as a self contained residential unit within a larger structure, containing several self contained unit or units all sharing a common entrance. They are usually single storey dwellings.
A maisonette is a dwelling which occupies 2 or more floors within a block. It can also be described as dwelling has its own access directly from the outside (i.e no communal corridor) but is not a stand-alone building.
mid floor flat
When assessing a flat the detachment may not be obvious
If the Access Corridor is unheated:
Flat A is an end terrace
Flat B is a mid terrace
If the Access Corridor is heated:
Flat A is an enclosed end terrace
Flat B is an enclosed mid terrace
In RdSAP it is necessary to indicate what type of heat loss the lowest floor of a dwelling has.
This applies to all dwelling types
Above partially/intermittently heated space
Above an unheated space
To external air
Same dwelling below
Another dwelling above
Roof heat loss type
Same dwelling above
For the purposes of RdSAP an extension is part of a property which has different thermal qualities to the rest of the house
Different roof types
Main property – pitched roof
Extension – flat roof
Main property – insulation at joists, 250mm
Extension – no access to loft, unknown insulation
A vertical extension is an additional storey to a property which can not be accounted for as a room in the roof.
Identify the vertical extension as an extension in the software, taking separate information for the whole extension area.
If the vertical extension does not cover the whole dwelling the part of the dwelling below the vertical extension must also be identified as an extension in order to specify the roof type as ‘the same dwelling above’.
Extension 2 Floor type: Same dwelling below
Extension 2 Roof type: Pitched roof
Main property roof type: pitched roof
Main property floor type: ground floor
Extension 1 floor type: ground floor
Extension 1 roof type: same dwelling above
Occasionally you may come across a house which has more than 4 extensions; in this situation you must ‘blend’ the extensions.
Merge the areas with the most similar age, construction and insulation, and make use of the alternative wall facility where appropriate.
A mezzanine floor is usually an intermediate floor between two floors in a building.
A mezzanine floor does not extend across the whole dwelling
This means part of the property has more floors than the rest.
It also means that the ceiling height for part of the dwelling is significantly bigger than the mezzanine section.
A room in a roof is defined by the following:
Access must be via a permanent fixed staircase that one is able to walk up and down facing forwards. (This does not include fixed loft ladders).
The height of the common wall must be less than 1.8m for at least 50% of the storey. Please note this does not include stud walls, gable ends or party walls. (The common wall is a vertical continuation of the external wall of the storey below.)
If the common wall measures greater than 1.8m for more than 50% of the floor then it is classed as a normal storey.
Measure floor area (internally); no need to measure room height or heat loss perimeter
If the 50% or more of heat loss walls at the eaves (common wall) are 1.8 metres high or greater , the space is classed a normal floor and you will need to take the measurements of wall perimeter (heat loss walls), room height and the floor area.
When you say a property has a room in roof it means the software makes the following assumptions
Effectively, when you specify a room in roof, you are saying that the majority of heat loss for the storey is through the roof rather than the wall construction specified in the software.
Presently, RdSAP assigns a flat roof area, and the remainder as wall area, based on the floor area entered
This is a useful estimation in most cases, however this may not prove sufficiently accurate in certain scenarios
If it is judged the roof room vastly differs from the default values, the software allows areas and insulation to be recorded separately
flat ceiling parts
It will also be possible to indicate in the software whether the room in roof is connected to another part of the dwelling i.e. extension.
in some cases it is not possible to get the Roof Room insulation levels. This is when default values are used by the software.
Room in Roof Quiz
Here are a few slides of properties
This is a dorma bungalow
The entire top floor is built within the roof structure, the cavity wall stops at the top of the ground floor
The dorma window is likely to be constructed using timber
The top floor has had a loft conversion and a large dorma window has been added
The dorma window has a different construction type to the floors below
The common wall type, solid stone, stops at the top of the 1st floor
Therefore the common wall is 0m on the top floor.
Another dorma bungalow
The top floor is built entirely within the roof structure and the common wall stops at the top of the ground floor
The common wall stops part way up the 1st floor
It is likely the common wall measures less than 1.8m
Measure the habitable space of the room in roof
Do not include the area behind stud walls, often used as storage space
Include the floor area of any dorma windows
A room in roof should always be measured internally
There is no need to measure the ceiling height or heat loss perimeter
If a single storey flat is located entirely in the roof, it cannot be entered as a Room in Roof: In this case:
A cellar or basement does not have to be a habitable space to be included in the survey.
Room in roof
2 Storey House
3 Storey House + room in roof
Basements (whether to include in the assessment) states 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.
If a porch is heated it should always be included in the EPC
An internal porch lies within the line of the external wall of the property, an external porch would protrude from the external wall, as shown in the image
Convention 2.09 states
Porches If heated always include (separated or not). If external and not heated, disregard. If internal, not heated and thermally separated,disregard
A conservatory must have at least 50% glazed walls and 75% glazed roof
Can be classed as separatedor non-separated
A conservatory is “non-separate” if it is thermally linked to the house, i.e. open plan or internal quality door separation
A conservatory with an unglazed roof is a sun room and should be treated as an extension
This conservatory is open to the rest house – there is no separating door
This conservatory needs to be included in the survey
This conservatory has an external quality door separating it from the rest of the dwelling
An external quality door is one which would be suitable as a front or back door
This is a sun room, it does not have at least 75% glazed roof so it cannot be entered as a conservatory in RdSAP
It should be included in the EPC as an extension unless all the construction, insulation and age details are the same as the main house
More than typical glazing should also by selected.
An Alternative Wall is thermally different to main wall type and cannot be accounted for as an extension
An alternative wall can be applied to all parts of a dwelling. This includes the main property and all four extensions
Wall area is required (excluding any apertures)
If property is identified as a flat or maisonette, there is now an option for a ‘sheltered’ alternative wall.
A sheltered alternative wall is situated between the dwelling and an unheated corridor, or stairwell. This option can only used for the main building part.
There are three features of the windows in a dwelling which must be recorded:
Percentage multiple glazed
Type of glazing
*(2002 is the date for England and Wales, 2006 for Northern Ireland, 2003 for Scotland)
Double glazing can be entered as units installed before 2002 or after 2002. The 2002 building regulations introduced a minimum standard for the installation of double glazed units. This is indicated in a number of ways.
Earlier double glazing has a more narrow air gap, less than 12mm. If it is not possible to identify the date of installation, then the glazing should be entered as pre-2002.
Secondary glazing should only be accounted for in a survey if units are installed correctly. Temporary additional glazing, such as cling film, should not be included in the survey.
Triple glazing can be identified by 3 panes of glass with 2 separate air gaps
within the unit. The glazed unit will appear wide in comparison to a standard
double glazed unit.
The BFRC Scheme is the UK’s national system for rating the energy efficiency of windows and is recognized within the Building Regulations as a method to show compliance for replacement windows installation
Each window rated by the BFRC has a unique label
This label will display the following information:
The rating level – A, B, C, etc…
The energy rating eg. -13kWh/(m²·K) in this example the product will lose 13 kilowatt hours per square metre per year.
The window U value eg. 1.6W/(m²·K)
The solar heat gain (g-value) eg. g=0.45
The effective heat loss due to air penetration (L factor) eg. 0.00 W/(m²·K)
RdSAP convention 3.10 states:
U-values and g-values can be overwritten only if documentary evidence is provided, which can be either a Window Energy Rating certificate (as defined by the BFRC) or manufacturer’s data. The U-value is for whole window, not centre pane.
Where the extended window data is used (when ‘much more than typical’ or ‘much less than typical’ is selected) you will now be required to record the orientation of each window
There will also be the option to include the U-value and g-values (if known and documentary evidence is available)
Draught proofing is a cheap and efficient method of saving both energy and money.
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
Types of draught proofing can include:
Self adhesive sealant strips
Spray foams (sprayed into gaps around windows)
Self adhesive sealant strips
RdSAP convention 3.11 states:
All external doors and at least 2 windows per building 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 glazing as being draught proofed, and single glazed windows and doors as no draught stripped
Include glazing in a non-separated conservatory
The percentage of draught proofed is [(number of draught proofed windows and doors) divided by (total number of windows and doors)] x 100
For flats, if there is an unheated corridor the door is assumed to be for the corridor only, i.e. not external and not included. If a flat has more than one door, the remaining door(s) are external and included.
It is also possible to enter the U-value for insulated external doors (if known and documentary evidence is available)
If the U-values of more than one door are known then calculate and record the average U-value
RdSAP convention 3.09 states:
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
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
Lights in the following locations are not included in the light count:
There are two methods to assess PV systems
Thepeak power can be obtained through the MCS certificate.
Pitch, Orientation and Overshading can be assessed on site.
The software will make the provision for only one type of turbine to be entered
If however, a property has two turbines that differ in both hub and rotor height they must be combined and entered as one
This is done using a calculation spread sheet which takes data of multiple turbine types and converts it into one figure
The spread sheet will be made available on the Stroma member’s area
This is another ‘yes/no’ option in the software
If yes, the assumption is a 2m rotor with a 2m hub height
This option will still be available but can be overwritten with valid documentary evidence
The data to be collected can be seen on the table on the right