No, not a case of the sniffles, but a how to deal with Class 1 and Class 2 flues in new dwellings.
A quick and simple way to make a new house fail a SAP analysis is to incorporate a flue without specifying a suitable appliance. Why? Because if no fire is specified SAP will default to the worst possible choice and this is frequently all that is needed to change a pass into a fail.
Even when there is no flue shown, SAP will assume that 10% of the heating requirement for the home will be met by a secondary system. If none is specified, SAP will specify one for you*.
Secondary heating appliances come in all types, some good, some bad and some awful. Where is the sense in having a 90% efficient central heating boiler which is supplemented by a 30% efficient fire?
A class 1 flue with an open coal fire in the grate is very inefficient and when the fire is not lit you have the equivalent of a large hole in the wall undoing all the good work of your expensive insulation. If a chimney is a ‘must have’ then specify a closed front gas fire or, even better, a wood burner. Wood logs or chips from well a managed source are classed as biomass and have an impact on carbon emissions that is close to neutral. Some of the modern appliances are also extremely efficient so it’s a win –win.
The same thing applies to Class 2 flues also. Never specify a class 2 flue without a fire, use a sealed front gas fire preferably with a fanned flue.
I sometimes come across the view that even though a flue has been designed into a dwelling I don’t have to take it into account if it is just for decoration or it will be blocked off. Unfortunately, if a flue is shown on a drawing it will be assessed, regardless of whether it is blocked off or not. The assumption being that a blocked-off flue can be unblocked later and brought into use. If a chimney is desirable just for aesthetic purposes, use a dummy one.
*There is a bit of good news on the horizon though. When the new Part L comes into force, on 1st October 2010, SAP will assume that, where no flue is specified, the main system will provide 100% of the heating requirement.
For more information or to book a test, call me on 01484 686649 or visit my website on http://www.hometestingyorkshire.co.uk/
I hope this helps,
Matt
A quick and simple way to make a new house fail a SAP analysis is to incorporate a flue without specifying a suitable appliance. Why? Because if no fire is specified SAP will default to the worst possible choice and this is frequently all that is needed to change a pass into a fail.
Even when there is no flue shown, SAP will assume that 10% of the heating requirement for the home will be met by a secondary system. If none is specified, SAP will specify one for you*.
Secondary heating appliances come in all types, some good, some bad and some awful. Where is the sense in having a 90% efficient central heating boiler which is supplemented by a 30% efficient fire?
A class 1 flue with an open coal fire in the grate is very inefficient and when the fire is not lit you have the equivalent of a large hole in the wall undoing all the good work of your expensive insulation. If a chimney is a ‘must have’ then specify a closed front gas fire or, even better, a wood burner. Wood logs or chips from well a managed source are classed as biomass and have an impact on carbon emissions that is close to neutral. Some of the modern appliances are also extremely efficient so it’s a win –win.
The same thing applies to Class 2 flues also. Never specify a class 2 flue without a fire, use a sealed front gas fire preferably with a fanned flue.
I sometimes come across the view that even though a flue has been designed into a dwelling I don’t have to take it into account if it is just for decoration or it will be blocked off. Unfortunately, if a flue is shown on a drawing it will be assessed, regardless of whether it is blocked off or not. The assumption being that a blocked-off flue can be unblocked later and brought into use. If a chimney is desirable just for aesthetic purposes, use a dummy one.
*There is a bit of good news on the horizon though. When the new Part L comes into force, on 1st October 2010, SAP will assume that, where no flue is specified, the main system will provide 100% of the heating requirement.
For more information or to book a test, call me on 01484 686649 or visit my website on http://www.hometestingyorkshire.co.uk/
I hope this helps,
Matt
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