I have still have the CD version of Stars. I just realised it is 2002 Issue 3.1, how time flies, so I have hundreds of historic calculations saved. I will try to update it with Stelrad now, the auto update link is broken on the 2002 version, that's why I thought it hadn't been updated.
I am now starting to quote
heat pumps for new builds on heat loss per square metre to save time, as it seems I have to quote 10 projects to get one!! 40-50W /m2 for new builds and around 70W for new refurbs and 100w /m2 for older properties with caviity walls and double gazing. I would hope not to use 150W/m2 even for solid walls and single glazed older houses, but I would be more careful with these and do a more stringent heat loss using STARs. I think the simplified SAP asessment operates in a similar fashion to the 'whole house boiler sizing', where you plug in the area of outside walls, age of property and location etc, but I am sure you will tell me there is more to it than that.
The amount of air changes are the killer for getting your accuracy in heat loss calculations, new houses have much less air change than the defaults in Stars, new builds now kitchens are 2, bedrooms 1 and lounge dining is 1.5/hour. Open flues in lounge can add another air change/hour. Stars alos tends to oversize bathroom radiators, it assumes a default 3 air changes and 22 degrees air temp, but not many bathrooms have 3 air changes / hour all day and are heated constantly to 22 degrees.
You never really know what the air change rate is on an older property. I have had very leaky old houses and some seemingly very air tight, old suspended ground floors can be particularly bad, especially if floor joists have rotted and the floor has dropped. It is safe to say that an old cottage with exposed beams and single glaze windows are usually well ventilated as well!!
Heat pumps not my favouritre product for an old house, it is safer to use a pellet boiler with radiators, at least is has some punch and the cost/kW capacity is much lower than a
heat pump.
Yes, I am MCS registered, I was assessed on the new version of MIS3005 for
heat pumps last November, I didn't realise that I wasn't in force at the time. I did the main 4 MCS technologies, solar pv, solar thermal, biomass and
heat pumps (ground and air).
I have always done my own heat loss calcs on stars or other software.