Is it worth it?

It seems every improvement costs money, and also many can save money, but be it cost to borrow money, or loss of interest on money used, there must be a common formula to work out if an improvement saves money.

I am told commercial wise it has to pay for its self in 25 years, any longer than that then not worth doing.

Interest rates have gone up and down in my live time, 15% interest on a mortgage is not unknown, and mortgage rates are a lot lower than many rates for borrowing money.

So if I buy a new fridge/freezer which uses 10% less power to old one, has a life of 7 years, and costs £300 will it pay for its self, and how will it compare with a unit which saves 15% also has a 7 year life and costs £400?

OK there are other factors, frost free keeps a more even temperature, so safer with upright types, but before we can work it out we need to work out the cost of using that money.

So if I replace all my TRV heads and install EvoHome which should reduce the heating bill, if it costs £1000 how much do I add to new bill to take account of money used cost?

I know I have money in bank so will cost me less than some one who has to borrow it, but if I use the money on heating then not used on car, and adverts tell us saving so there must be a formula used on how much the money used costs.

The theory is the same as business cspital expenditure, payback period.

You want to know when your investment has paid back and also future savings.

The problem is that you need to make a number of predictions, making accuracy difficult. Ie future interest rates, energy cost, lifespan of item etc

Also you would have to make a judgement on the difference between offical quoted energy usage of say a fridge, compared to real world usage.

If you wanted to really go for it, you could do pareto analysis of each potential investment and rank each one.

There is a trade off between convience and power saving. We use a tumble dryer rather than putting clothes on a line or airer.

The problem in UK housing stock is the fabric of an older house cant be improved at reasonable cost to make a big difference to reducing heat loss.

I doubt you will get any usefull saving , more effective to just drop the stat 1 degree and turn off rads in unused rooms.[And its free]

ericmark said:

So if I replace all my TRV heads and install EvoHome which should reduce the heating bill,

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Unlikely any real savings will be made.

To go from no controls to some would be a substantial saving.
Once you have semi-decent controls and use them properly, changing them for other types may save a few %, but nowhere near enough to cover the cost of the changes within a reasonable time.

Products such as Hive and Nest only provide big savings for those people who are too stupid or lazy to turn their heating off when the house is unoccupied. Such individuals could make big savings just by setting the timer they already have.

Same as people who are shoehorned into replacing a working older boiler with a new one just because it is more efficient. Spending £2000+ to save £200 per year on gas is a pointless exercise, the 'new' boiler will be bust before it saves enough to cover it's own costs.

Then there are things which are just a total waste of money in all circumstances and never get anywhere near covering their own installation costs - solar hot water installations costing £1000s, all to save £50 per year.

Rather surprised on moving house, mothers old house is very well insulated, however between lower and upper floor there is no insulation so upstairs the problem is over rather than under heating, the TRV rarely turns on an upstairs radiator, so in real terms only down stairs rooms need controlling.

Even down stairs turning off heating at 9 pm it rarely dropped to 16°C by 6 am when it comes on again. The fabric of the building stores heat well, which means any idea of altering temperatures through the day are really not going to work, I had big ideas of using eTRV heads and setting temperatures 20°C at 6 am dropping to 18°C at 9 am then raising to 21°C in the evening say 7 pm to 10 pm then 16°C overnight, great in theory, but in practice at 9 am lucky if got to 19°C and set at 21°C in the evening great to watch TV but too warm to sleep. In real terms 1°C is about the maximum you can lift and drop temperatures.

As to geofencing forget it.

However I would say we heat the home around 50% of the year, so any device which can produce less heat by upgrading to new technology is only going to save energy for half of the year, unless using air conditioning, the excess energy may make it more uncomfortable in the home, but not cost.

The problem is not all fuels cost the same, so heat with gas rather than electric will save money, but not energy. But if we want to for example compare a gas hob to an electric induction hob in real terms how do we do this?
1) Gas cheaper than electric.
2) Can't use a wok with electric as pan too heavy.
3) The gas hob is cheaper than electric.
4) Electric more efficient than gas.
5) Electric safer than gas.
However then comes the hard bits.
6) Gas produces water as it burns so it needs more ventilation. This in turn means more air changes so heating costs go up. But gas also heats the kitchen so rather hard to measure the extra heating costs, but it does need a cooker hood linked to outside not a simple filter.
7) The gas hob is cheaper than electric, however fitting costs may change this.

So if one needs a new hob the answer is easy, all in all the electric induction hob wins hands down, however if deciding if worth changing to electric that is completely different. I noted my daughters 5 kW gas hob boils water slower than a 2.8 kW electric kettle, however a 3.8 kW induction hob beats the electric kettle, so from that we can assume an induction hob uses less than half the power to a gas hob, so running costs likely equal to each other.

But £500 to change from gas to electric with 10% interest on money over 10 years life need to add £25 per year interest plus £50 paid off so £75 a year to change it. So unless the gas hob heats up the kitchen to the extent where air conditioning is required, then not worth changing until the gas hob fails.

The same applies to fridge/freezers, and new boilers, by time one adds interest to the money used then the costs for fitting new more energy efficient units does not make financial sense. My old boiler is 35 years old, I am told I can expect 7 years from a new one, so if it costs £500 for a new one looking at £96 per year saving before it breaks even, working at 10% but £74 per year working at 1% so cost of borrowing money can easy tip the balance. OK I would prefer the reliable 25 year old over the less reliable new one, and if the new one needs an annual service that also needs including.

I suppose I also have to consider what ever I get unlikely to be required to last 25 years. By that time I will be over 90 so likely dead or in an old peoples home. Also can't take any money with me when I go, but still looking on how to price upgrades so to work out if worth it.

flameport said:

Unlikely any real savings will be made.

Products such as Hive and Nest only provide big savings for those people who are too stupid or lazy to turn their heating off when the house is unoccupied. Such individuals could make big savings just by setting the timer they already have.

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I am not sure how much can be saved using a Nest thermostat or other modulating type when compared with simple on/off like Hive? However I made a mistake, the original thermostat was a Honeywell Y6630D which is rather expensive (£120) and not programmable, so I went to a Horstmann HRFS1 much cheaper (£67) and programmable. What I had not realised was when the Honeywell Y6630D batteries go flat it fails safe, the central heating turns off if no signal every half hour, also it starts to switch on/off a degree or so before set temperature to reduce the hysteresis. There is a good reason for the £120 price tag.

Even with Nest using the OT1 and OT2 terminals to regulate the boiler, if using eTRV heads, one if internet fails so does the connection to heads, and two all heads would need to be set to same temperature so not really that good. Hive is a total waste of money as not Open Therm enabled.

Hive at £180 is programmable and does have fail safe, maybe there are cheaper wireless programmable thermostats with fail safe? But it like the Honeywell Y6630D has anti-hysteresis software, not sure this is what is wanted for most wall thermostats? OK with my old boiler, but modern boilers are designed to modulate, so control needs to match that, so in real terms the TRV does the control, all the wall thermostat does is auto turn the boiler on/off when otherwise it would be cycling.

So thermostat in the coldest down stairs room with no outside door or alternative heating turns system off when all rooms are warm, if correctly set, whole idea is to reduce cycling, so to have a thermostat that cycles before it hits set temperature really defeats point of having it to start with.

Wow! Lots of calculated logic. I simply just replace things when they need replacing taking into account price and efficiency. An A+ rated freezer to A++ is not going to save more than a couple of quid a year in my book. So if it's much more expensive it's not worth doing. For me one of the better things I did was switch the light bulbs to LEDs. Especially the downlighters in my old kitchen. Went from 750w to 45w for about £45. With the wife and kids unable to turn lights off this wouldn't take long to payback with the many GU10 halogen blown bulb replacements.

pilsbury said:

An A+ rated freezer to A++ is not going to save more than a couple of quid a year in my book. So if it's much more expensive it's not worth doing.

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Not quite that simple.
1) The standards to get the A++ rating for freezers change with type, so you can't compare a chest freezer with an upright or even a frost free to non frost free, or built in to free standing, or those designed to work in high temperatures to those designed for our climate.
2) With upright having a circulating fan means you don't get warm spots, and with the circulating fan required with frost free you can also remove draws if required.
3) There are also three phase units with inverters which are much quieter than old single phase and tend to have a long warranty, in some cases motor speed is controlled rather than simple on/off.

Central heating has the same, if you select the chair in the room most used and the temperature varies 18°C to 22°C then not really that good, but 19°C to 21°C is likely good enough, although 19.5°C to 20.5°C would be better. Using eTRV you can get this control, same with a modulating thermostat, but on/off thermostat or a TRV with a wax pellet then your unlikely to get that control.

Even something as simple as LED instead of tungsten, it only saves energy if you don't want the heat, and often you want the heat.

ericmark said:

Even something as simple as LED instead of tungsten, it only saves energy if you don't want the heat, and often you want the heat.

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bearing in mind that energy from electricity costs four times as much as energy from gas, so a light bulb makes an expensive heater, and has no thermostat

JohnD said:

bearing in mind that energy from electricity costs four times as much as energy from gas, so a light bulb makes an expensive heater, and has no thermostat

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One your assuming the person has gas, and two still wasting resources swapping to LED even if it does save money.

However to me the big reason to go to LED has nothing to do with energy or money, it is down to less maintenance. Swapping a bulb from compact fluorescent to LED makes sense, they start quicker, more light per watt, and last longer, swapping a fluorescent tube for LED however does not, as less light output and shorter tube life as I found to my cost. Also bulbs are quite cheap, but tubes are quite expensive, and when fluorescent fail they give warning on the way out, when LED fail working one second then not the next.

ericmark said:

I am told commercial wise it has to pay for its self in 25 years, any longer than that then not worth doing.

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What is an acceptable return on investment varies massively by industry, corporate strategy and type of change. If the investment holds a residual value, eg investing in heavy machinery, then you may be comfortable with a longer payback but if you're buying a service or such that has no effective resale value you're likely to want a quicker payback... if in 1993 you were trying to decide if to invest in Microsoft Office v3 for your 500 office computers you'd have failed horibly in your calculations if payback was only going to be acheived by this year.

The calculation on when you'll break even is exactly the same though but you need to make assumptions around inflation, interest rates, cost of fuel and/or consumables etc. Depending on what the investment is, you may need to look at things like your time, enjoyment etc which have no direct cost but could still be a significant contributing factor.

Calculations arent too hard to do, its making realistic assumptions that are. Given many of the factors are compounded then the further out you try and project the more uncertainty you have. The only times I've gone beyond a 5 year forecast is when a business case has had very strong soft benefits and/or buy in but the numbers people were willing to commit to wouldnt make the business case stack up.

On my personal spend I wouldn't spend to save. I buy a new freezer because the old one is unreliable or too small for our needs etc. I buy a new TV because I want some new feature like 4K. Even with a car I'd argue my decision is more about reliability and convenience than actually the cost of having it repaired/getting alternative transport.

I doubt I'd ever load up Excel and work out if having 1 breakdown a year but cheap repairs is better than having a brand new boiler thats expensive to buy/fit, will hopefully have no breakdowns a year but will be more expensive to fix when it does breakdown and is 5% more efficient in real world terms... I simply don't want a cold shower in winter so will replace it as soon as it becomes unreliable.