Rollalong Ltd are specialists in permanent offsite construction who contacted us via our website with an interest in learning more about whether calculating project specific psi values might better represent  their construction method in a residential project they were working on. As always we took the time to discuss the project in detail with them so that we fully understand what they were trying to achieve. Following our discussion we were commissioned to calculate a suite of 15 psi values for a light steel frame residential project requiring both 2D and 3D modelling. All we needed to get started was a set of dwg drawings from which to model the junctions. We completed an initial set of calculations within the timeframe agreed with Rollalong and issued our calculations for review and comment. Following on site changes in materials we were instructed to make alterations and issue a revised set of calculations which achieved the following results

 

Junction Name

SAP Ref

Comments

Default

Results

% reduction

Window Head

E2

3D 

1

0.017

98%

Window Sill

E3

3D

0.08

0.023

71%

Window Jamb

E4

2D

0.1

0.053

47%

Ground Floor Sidewall

E5

3D

0.32

0.096

70%

Ground Floor Endwall

E5

3D

0.32

0.104

68%

Exposed Floor (Normal)

E20

3D

0.32

0.135

58%

Exposed Floor (inverted)

E21

3D

0.32

0.158

51%

Intermediate Floor between Dwellings Sidewall

E7

3D

0.14

0.049

65%

Balcony

E23

3D

1

0.219

78%

Flat Roof to Parapet

E15

3D

0.56

0.148

74%

Corner

E16

2D

0.18

0.066

63%

Party Wall between Dwellings

E18

2D

0.12

0.033

73%

Staggered party wall

E25

2D

0.12

0.024

80%

 

These results achieve an average improvement over default Appendix K junction heat loss values of 69%. This performance enabled Part L calculations to comply easily with the TFEE without any additional over specification and cost in the U Values in the floor, walls, roof or windows across this project. It also permitted the dwellings to work to a more realistic air test result i.e. 5.00.

Often projects over engineer the fabric performance of floors, walls, roof and windows to compensate for a poor representation of heat loss through the thermal junctions, however, this was not the case on this project.

Adam from Rollalong doors said the following about the service that we provided “My overall experience from Darren Evans has been very positive, when we approached Darren Evans to provide us with thermal bridging calculations, we were on a very tight timescale due to project constraints. These Targets were exceeded and information delivered 1 week early which was good for overall design target dates. The team I dealt with were very professional and worked well, communicating during the task and process. In terms of monitory costings Darren Evans was not the cheapest but also not the most expensive company we were quoted by. But I felt that the manner in which the initial communications were handled and information provided gave me confidence in the competency of the company. We have just engaged with another enquiry with Darren Evans to be completed in the new year”

Working to support the construction industry to achieve a more energy efficient housing stock is something that we are passionate about.

Get in touch:

Our BREEAM Assessors are here to answer any of your queries, or if you would like a FREE quotation, please give us a call on 0333 5777 577 or fill in our contact form and we will get back to you.