Gas Consumption

Whilst reducing electricity consumption was relatively easy, gas proved to be more of a challenge.  Out house fully lives up to the Victorian ideal of being well ventilated and is none too well insulated.  Being an hopeless romantic, I was attracted by the idea of ripping out the gas boiler to make way for a wood burning stove and grudgingly installing loft installation.  All I had to do for for a cheap carbon neutral lifestyle would be to pick up a log whilst taking the dog to the canine urinal, sometimes known as the woods.

At some point I remembered I had trained as an engineer and decided to have a rethink.

Current Consumption

Our current gas consumption is around 27,000 kwh/year, broken down roughly as shown in the graphs below:

Peak consumption is in December when its cold and there are more people in the house some of whom celebrate Christmas with their annual bath.

The peak energy requirement is approximately 20 kw.

SAP

A SAP 2001 analysis (a DIY and unvalidated Excel spreadsheet) of our home suggests that our energy requirement is approx. 32,000 kwh.  Whilst SAP does not take into account lifestyle, it does provide an insight into a home's energy consumption and can provide a means of evaluating the costs and benefits of modifications.

The Plan

The plan is based on our lifestyle (an inappropriate term for maintaining three teenagers and a dog) and results of the DIY SAP spreadsheet.

Fit Cylinder Thermostat

Our central heating boiler has no effective thermostatic control.  A crude estimate of our hot water consumption, suggests that only 50% of the gas consumed by the boiler, ends up in the bath and that remainder just keeps the boiler casing warm.  Estimated saving 4,000 kwh/year for an expenditure of around £100.

Loft Insulation

The SAP analysis suggests a saving of 10,000 kwh, however, in our case this estimate is probably high as we use the central heating sparingly, So my expectation is 4,000 kwh for an outlay of around £300 and the life-enhancing benefits of a large DIY job.

Burn more wood

We are fortunate in having two useable open fireplaces, these are a good way of heating a single room.  For the internet connected work-from-home type, a wood fire provides a better displacement activity and endless cups of coffee and biscuits.  Possible savings, 1,000 - 2,000 kwh in return for being perceived as the local weirdo who goes round picking stuff out of skips.

Investigate Zone Control

At the time of writing, this is still under investigation.  My perception is that the central heating can not be controlled by a single thermostat.  Since the advent of central heating, it seems that thermostats have been installed in the hall or on a landing, a place no one uses.  Secondly, that zone control should be at the room level.  If there are only two people in the house, one downstairs and the other upstairs, both zones will be on and six rooms will be heated rather than two.  The expectation is a saving of 1,000 - 5,000 kwh for quite a lot of money.

Investigate Solar Water Heating

Whilst I'm attracted by the idea of energy self sufficiency, to me it seems logical to minimize consumption first.  My perception of solar water heating is that a typical installation (2 - 4 square metres) will produce something like 2,000 kwh during the summer months for a outlay of between £2,000 and £4,000.  This puts it low on the priority list.

Whilst this scheme may work for our household, I hope that the same thought processes will will help people find solutions which work for them

Then and Now

It is interesting to reflect on the heating arrangements when the house as built and those in place now:

	Then	Now
Hot Water	Coal fired range with a fire most of the time	Central Heating Boiler
Space Heating	Six open grate coal fires.	10 Steel radiators
Cooking	Coal fired range with a fire most of the time	Gas Cooker
Control System	Capacity and willingness to carry coal and ash	Ineffective system of thermostats.
Heating Capacity	30kw	20kw
Energy consumption	25,000 - 40,000 kwh/year	27,000 kwh/year
CO2 Emissions

At a guess, when the house was built, coal consumption was between 3 and 5 tonnes/year (calorific value of coal assumed to be 8,500 kwh/tonne)

Implicit in the original heating arrangements was a control system based on getting the best value from the coal bill. It is probable that in the winter months, a fire was burning in only those rooms being used, thus there would be 10 - 15 kw of heat keeping a couple of rooms comfortably warm, albeit with inefficient use of coal (a coal fire is less than 20% efficient).  The current arrangement divides 15kw between 10 spaces, only two of which may be occupied and one of those by a dog whom we don't care about (he is welcome to join us in the living room).

As for the range, whilst some modern cookery writers eulogise over the ability of these things ability to produce perfectly cooked food, most of the women in our family who remember them (and it was women who had to deal with these things), recall through gritted teeth the joy of keeping them alight and clean.  They all rushed out and bought gas cookers as soon as they could.  Much the same goes for laying and raking out open fires.

Page Updated: 13-Mar-07

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