On this page are my musings on heat distribution. You may care to “Save As” – download it onto your computer – then open it or simply veiw it on line.

Firstly,

Likely heat losses for the building as a whole using all elements of the external walls, floors and roofs. Note that I did forget the north wall of the kitchen (and front door) but have now allowed for the former. U values are estimated and likely to be better that estimated. No attempt on this for air changes. See later.

A spreadsheet of the likely needs of each room for heating in Kwatts with respect only to SURFACES OF EACH ROOM.

To cater for infiltration (air changes) this spread sheet was extended and calculations done of the heat losses for various types of room (bedroom 0.5 to bathroom 2.0 room changes per hour) for the likely temperature difference ignoring internal walls. Thus, every room in the house had its own heat loss calculated both for steady state and air changes and the resulting spread sheet gave the heat requirements for each room.

For those with UFH this figure was divided by the floor surface area available for UFH to provide the necessary number of watts per square metre needed to achieve heating to the target temperature of 18 C when the outside was -1 C.

For those rooms with radiators, mostly on the first floor, I calculated (using the Delta T of 13.5 and an “n” Radiator Constant of 1.35) that the reduction factor  appropriate for that was likely to be appropriate the reduction from DT50 to 13.5 K was 0.17, so the radiators were likely to be about 20% efficient compared with a delta T of 50 C. This equates to 600 watts per square metre. On that basis I worked out the area of radiator needed for each room and was able to determine that for the Dry Room a supplementary radiator was needed and that the kitchen will be cold unless  we can increase area the heat supply by putting pipes in the wall / plaster.

A spreadsheet of the likely needs of each room for heating in Kwatts   is here. The firm EngDesign are, as I type on the evening of the 1/6/2007, checking all my calculations and will be choosing the precise radiator types and sizes and outputs.