Heat loss calc in old house renovation

[jayroc2k]

I am at loss on how to calculate heat loss for the ground floor of a victorian house with new extension.

 

It is an end of terrance house with the following

- solid wall 220m brick on the front (4m) and side (7m)

- new timber double glazed sash bay windows to the front

-  70mm celotex between the joist floor

- new 6m x 5m extension added, new walls full fill cavity to 0.3 u value

- double glaze 3.6m x 2.4m sliding doors

- 2m x 3m double glaze roof window

 

All space is open. most heat loss calc assume a single type wall construction for the space.I need to know by next week if underfloor heating is feasible for the given heat loss.

 

Most underfloor only give 70w/m with wood flooring

 

thanks

[Ferdinand]

One way would be to treat it as two volumes with 2 separate calculations at the same internal temperature.

 

Or have you tried the Heatloss Spreadsheet and U Value calculator from @JSHarris.

 

The most complex calculation you would need to do yourself seems to be an area-weighted average u-value for your walls.

 

For each type of wall, that is u-value of section of wall * area of that section of wall, and add them all up to give a weighted value and divide by total area for an average u-value. I think that is right.

 

I am sure we can pitch in and help.

 

My initial thought is that if it is half just solid walls with no extra insulation in an end terrace then no ufh system on earth would deliver enough but it will be worth the calculation to check it and help identify options if necessary. Even boarding out to building regs standards may not be enough, based on my own experience.

 

Ferdinand

Edited February 9, 2017 by Ferdinand