Category Archives: House

Why I didn’t buy .. spray foam insulation.

I recently signed up for a free home energy survey. After various questions about my home – so not much of a survey – my visitor alighted on spray foam insulation in the loft as a technology that should be of interest to me. Claims included:

  • Spray foam insulation would dramatically reduce my heating bills (“save upto 50% on future fuel prices”) – a sum amounting to hundreds of pounds of savings annually.
  • Spray foam insulation would result in a better EPC rating and thus increase the resale value of my home ( “.. Eco measures are adding up to 14% on property values.. “).
Spray foam loft insulation

Given that the salesman attached some credibility to the UK’s national EPC scheme which requires an assessment of each home before sale as evidence for the buyer, then a good start point would be to see what the EPC said about my loft insulation. According to my most recent survey from September 2015 (so almost 4 years old) my home, at that time, had 100 mm of loft insulation between the floor joists with a recommendation to increase to 270 mm thickness by placing another layer of insulation across the top of the floor joists which would reduce my energy consumption by £219 over 3 years. £219 over 3 years amounts to £73 annually. In fact, since the survey was completed, I added the additional insulation recommended in October 2016 so that saving has been made and 1 point improvement on the EPC scale obtained. According to Which? magazine quoting the National Insulation Association “100mm of spray foam insulation is equivalent to around 170mm of loft insulation” so my 270 mm of conventional insulation may provide more insulation than the proposed spray foam insulation. My £73 annual saving from the EPC is far from the hundreds of pounds annually being claimed by my guest. Thus I don’t think the claimed savings are justified.

Floor level loft insulation

Then there’s the question about what the impact on my EPC rating would be. The extra 170 mm added post-2015 survey added 1 EPC point to my house rating. That’s not a big increase.

Then there’s the question about what the value of that 1 point on the EPC rating would be. According to the EPC certificate itself the indicative cost of adding 170 mm of insulation is £100 to £350 pounds. I actually paid £300. It’s not reasonable to believe that any additional value added to the home exceeds the cost of doing the work for such a small scale job. The salesman actually left a written claim that “Reports now showing that Eco measures are adding up to 14% to property prices” – I suspect that you’d need a lot of Eco measures (well beyond loft insulation) to add 14% to property prices which would be around £70,000 for my home!

Then there’s the overall question of the cost. Bearing in mind that my current insulation cost £300 and may be equally if not more effective than the spray foam then what was the spray foam quotation for? Discounted to £7,658 with marketing testimonials after the usual call to his boss to get “approval”. Which? reckons £2,500 – £3,000 for a 3-bed semi, whereas I am blessed with a substantial 4-bedroom house so it might conceivably be double the price; but for any investment on that scale I’d want to see competitive prices not just one.

Finally the question arises if I really wanted to spend £7,658 on energy efficiency would more loft insulation be best value? Our old friend the EPC has a proposal in that sort of price range, and one that it believes delivers greater savings. And that proposal is.. floor insulation for my solid concrete floors. The EPC suggests that this can save £132 annually – 81% greater savings than that extra 170 mm of loft insulation albeit at up to 20 times the price. However I already ruled out floor insulation on grounds of poor return. (My guest wasn’t persuaded as to the value of floor insulation, but a check of EPCs on similar neighbouring properties by different surveyors all identified floor insulation as a greater benefit than more loft insulation)

Recommended measures from EPC

So for me the answer is clear – I don’t see any value in spending £7,658 on alternative loft insulation. For you the answer might be different – you might be planning to convert the loft into dwelling space in which case you want insulation against the tiles/slates rather than at floor level. However if you just wanted storage space then other solutions like a shed, storage unit or skip (!) could easily prove to be better value.

The Big Picture

After a series of quite detailed posts, I think that the time has come for an updated high level overview of what we have.

Heat loss from the home

We moved to our early 1970s house almost 4 years ago bringing with us our electric vehicle. The house had already been refurbished with new double-glazed windows, had cavity insulation (although that wasn’t recorded on EPC so must have predated the prior owners), and a token level of loft insulation. The existing gas boiler was arthritic, couldn’t heat the whole house, but was quite good at heating the header tanks in the loft! We had gravity-fed gas hot water (i.e. no thermostat or pump on the cylinder) which was completely obsolete, the cylinder dated back to the building of the house and had no immersion heater (although we had the wiring for one). So what did we do?

Space heating:

Eve Thermo eTRV
  • We substantially increased the loft insulation to reduce heat loss.
  • We had a modern condensing gas boiler installed to improve efficiency.
  • We updated to smart controls using eTRVs to set both temperature set points and schedules at room level. I built a smart interface to the boiler so that heating can be enabled remotely. I programmed a series of rules into Apple Home allowing the smart thermostats to enable the boiler when any thermostat wants heat and disable it when no thermostat wants heat. Some rooms also have additional rules linking heating to open windows or movement sensors. All of this reduces heat losses by only heating rooms that are (or will be shortly be) in use.

Electricity supply:

Solar panels
  • We installed our own solar panels given 4 kWp generation. (I also own a small share of a solar farm although there’s no contract that I’m aware of between that farm and my home energy supplier)
  • I invested in an immerSUN to maximise self-use of our own solar by enabling loads when surplus solar is available.
  • We switched to a green electricity supplier so when we need to buy electricity it comes from renewable sources.
  • We bought a small storage battery 4 kWh to store some of our solar production for use later in the day. Subsequently I can also use it in winter to buy when the electricity price is relatively low to avoid buying when the price is relatively high.
  • We chose a dynamic smart tariff to buy electricity at the lowest price based on market prices established the day before. The prices change each half hour and are established in the late afternoon on the day before.

Water heating:

Hot water cylinder
  • We replaced the old hot water cylinder with a modern insulated one (to reduce heat loss) with a low immersion heater (to allow more of the water volume to be heated).
  • Our principal water heating is now by diverting surplus solar electricity proportionately to the immersion heater, that’s backed up by the gas boiler which is enabled briefly in the evening for water heating in case the water isn’t yet up to temperature, and when the electricity price falls below the gas price I can enable the immersion heater on full power.
  • All accessible hot water pipes are insulated.

Electric car charger:

Electric car charger.
  • I built my own electric car charger that takes an external radio signal to switch between four settings 0, 6, 10 and 16 Amps to help me adjust consumption to match to availability of output from my solar panels. (Subsequently such products were developed commercially with continuously variable current limits, but the limitations of my immersun and on/off radio signal don’t allow me to go quite that far. Having said that my car only does 0, 6, 10 and 14 Amps so I would gain no benefit from a continuously-variable charger paired with a 4-level car).

Smart electricity controls:

Smart controls
top: HEMS (to manage bought electricity) and junction box
mid: radio transmitter (to car charger)
bottom: immersun (to manage self-consumption)
  • We have two systems for smart control of electricity:
    1. The immersun to maximise self-use of our solar electricity by proportional control of loads.
    2. A HEMS to manage the purchase of electricity (when necessary) at the lowest price by maximising consumption when the price is lowest.
  • When both systems want to enable loads (because the bought price is low and we have a surplus from our own panels) then cost is prioritised, so we’ll buy from the grid any demand not being met from our own panels.
  • Both systems are linked to 3 devices:
    1. Battery storage. The immersun is configured to work alongside the battery storage with the battery storage as the top priority to receive surplus solar PV. The HEMS can switch the status of the battery as required to charge from the grid when the price is lowest, or to discharge when the price is highest, or indeed to revert to default behaviour.
    2. Car charger. Second priority for the immersun after battery storage.
    3. Immersion heater. Third priority for the immersun after car charging.

The future

I have no firm plans for the future. I’m toying with adding to the HEMS various features including:

  • Making the display switch between GMS and BST as appropriate (it’s all UTC at the moment).
  • Edit configuration via the web interface rather than a virtual terminal.
  • Control a domestic appliance. Our washing machine was replaced relatively recently, but the dishwasher is playing up a little and may be a candiadte for HEMS integration where the optimum start time is selected to deliver lowest energy price.

Save energy — 19 free energy saving tips

Today I received the following 19 free energy-saving tips (click image for original article).

I quote the article here with my own observations.

Saving energy isn’t just about helping you to save electricity or be more energy efficient — it’s also a great way to save money.

We all know we could do more around the home to save energy, but where to start? While some of the biggest energy savers require time and money there are still plenty of lifestyle changes you can make that will save energy, and money.

With just a few simple changes to your lifestyle and your home, you could be saving hundreds of pounds on your heating, gas and electricity bills.

So, if you’re looking for ways to cut down on your spending, try these 19 free energy saving tips.

How to save money on heating

  1. Stay warm, cut costs. Turning your thermostat down by 1°C can save you as much as £60 per year. Also, keeping your heating on constantly on a low heat could potentially save you more money than switching it on and off for big blasts of heat. This is where getting to know and understand the timer settings on your thermostat will really pay off.

That I can see both ways. On the one hand not stressing a condensing boiler too much can keep it in condensing mode, and thus increase its efficiency. However keeping the home unnecessarily hot will increase the heat loss to the outside world (which is proportionate to the temperature difference between inside and outside) so an unoccupied house at an elevated temperature will increase heat loss, but might make heat more efficiently.

Also for many people, timers and thermostats are two different components and the use of the timer turns the heating on and off – not between two alternative temperature set points.

Our own smart heating does in fact switch between a high and low temperature (not on and off) but at 10C the low temperature is such that room temperatures don’t generally fall to the low temperature before high temperature is demanded again.

  1. Get cosy. Wearing more jumpers, socks and slippers around the house, and putting an extra blanket on the bed means you won’t be tempted to turn the heating up.
  2. Turn the pressure down on the power shower. A high-pressure power shower is a great luxury to have but you’d be surprised how much water they use – sometimes even more than a bath.

Be efficient with cooking

  1. Save time and stock up. If you’re going to use the oven, bake a few meals at a time to get the most out of having your oven on. After all, oven’s don’t allow us to heat one shelf at a time so why waste your heat?
  2. Heat your home with cooking. Leave the oven door open after cooking to let the heat warm your kitchen. The oven might give off enough heat for you to adjust your thermostat, a far more efficient use of that stored heat than throwing it out of your home with an extractor fan.

Heat from the oven after cooking certainly does heat the kitchen, but personally I would wouldn’t leave the oven door open which provides too much of a heat rush – I prefer to leave the door closed and allow the same heat to move into the room more slowly.

I wouldn’t adjust the thermostat – it’s goal is to control to a comfortable temperature. Does the comfortable temperature change when you’re cooking? If you’re too hot when cooking the thermostat (potentially a TRV in the kitchen) will already have turned the heating off.

As to extractor fans, their purpose is to remove steam from boiling pans and save energy by significantly reducing condensation. Turning off the extractor fan while generating steam is a false economy.

  1. Let the dishwasher do the dirty work . Avoid pre-rinsing the dishes in hot water. Save water and energy by just scraping the dishes before they go in.
  2. Make things easy for your fridge and freezer. Keeping them full means they don’t have to work as hard and therefore they use less energy. Empty space in your fridge or freezer wastes not only space but energy too.

Again not so sure about this one. In general the energy to run a fridge or freezer will be a function of the temperature difference between inside the freezer and the room in which it is found. I can have assume that this point relates to the frequency at which the door is opened where an empty upright fridge or freezer will rapidly dump cold air into the room, whereas a full fridge or freezer has less cold air to dump.

  1. Use the right ring for the right thing. If your cooker has a small ring, use a small pan. You might only be heating up a small meal, and doing so in a big pan wastes a lot of energy. Conversely if you try and heat a large pan on the small ring you’re more likely to end up heating for longer than saving any money or energy.

Be efficient with washing.

  1. Shrink your bills, not your clothes. 90% of a washing machine’s energy expenditure is spent on heating the water, so if you wash your clothes at 30-40 °C you’re saving significant amounts of money.
  2. Hang up your laundry. Air-dry your laundry rather than tumble drying it, particularly if there’s warm or windy weather. What’s more nothing smells better than air-dried clothes.
  3. Save yourself ironing time. Take your clothes out of the dryer before they’re completely dry – they’ll iron much quicker and you’ll use less energy on your drier.

Energy efficiency and electricity saving tips for your appliances

  1. Switch it off and save. Unplug all the appliances that you aren’t using regularly – even chargers continue to use electricity when they aren’t charging. Also, make sure you’re not leaving appliances on standby: it may be easier but it’s also a guaranteed way to waster energy compared to turning things off at the socket.
  2. Get the kids involved. Play energy-saving games with your kids. Get them to spot the areas in the home where energy is being wasted and where lights, switches or appliances have been left on.
  3. Let the sunshine in. On a sunny day, opening your curtains will let warmth into your house, but when it’s colder or the sun goes down don’t forget to close them to keep that heat in.

Be efficient with your whole home

  1. Get free cavity wall insulation. There are now government-backed full and partial grants available to help you pay for insulation if your home has cavity walls. Getting this done could save you around 15% on your fuel bills, so you could be saving on average £98 a year. Even if you don’t receive money from the government insulation is still worth it in the long run.
  2. Get free loft insulation. Because heat rises, as much as 25% of the heat in your house could be disappearing into your loft space. What’s more, even older properties that already have insulation in place may not have the recommended levels, particularly if it was installed in the 1970s or 1980s. If you apply for a loft insulation grant, you could save about 19% on your fuel bills – which works out at an average of £128 per year.
  3. Get free solar panels. Having solar panels installed on your house could save you as much as a third on your electricity bills. What’s more, thanks to the government’s Feed-in Tariff scheme solar panel installers get paid for the energy generated, so they may install them for free.

Indeed they might install them for free, but they do so because they get a good return on their investment via the feed-in tariff. If you have the capital available pay for it yourself, get the feed-in tariffs for yourself, and avoid any legal issues with rent-a-roof if you choose to sell your home in future.

  1. Apply for an energy-saving grant. There are plenty of energy-saving grants available to help with the cost of home improvements.

Don’t overpay for the energy you’re using

  1. Compare gas and electricity prices with to make sure you’re on the cheapest tariff for you. It only takes a few minutes.

Annual Energy costs

I was reading a newspaper article earlier which highlighted a 3 bed semi with annual energy consumption costs of £500.  Our net energy consumption costs for my early ’70s 4 bed detached in 2015/6 was £400.  That includes charging my electric car.

img_0591

The house has:

  • A-rated gas boiler (Dec 2015),
  • A-rated double glazing throughout (prior owner),
  • C-rated hot water cylinder with bottom-entry immersion heater and all accessible hot pipes insulated (Dec 2015),
  • 7 day timer (prior owner) with Thermostatic Radiator Valves (TRVs)  throughout (except hall and 2 towel rails – Dec 2015),
  • Standard cavity fill and 4″ loft insulation (prior owner, now nearer 10″ but Oct 2016 installation outside 2015/6 data window),
  • Almost 100% low energy bulbs (mostly Sep 2015),
  • 4kWp solar panels (Sep 2015) with energy management system (Sep 2015) with remote monitoring (Mar 2016) directing surplus PV to car charger (Apr 2016) and/or hot water cylinder (Dec 2015), and
  • Economy 7 electricity (Oct 2015).

I spent £1,000 on gas and electric in 2015/6 which was partially offset by £600 revenue from my solar PV giving net costs of £400. Given that some of the above were introduced during the year, a full year’s use should reduce consumption further.

 

 

We have moved

Well, after nearly 20 years in the previous house the time came to move. What had started as “One man’s journey” became a couple’s journey and then a family’s journey and eventually the point was reached that enough was enough, or rather non-enough was not-enough when it came to space. A journey that started with my wife proposing a new conservatory (opposed by yours truly) ended up with a significantly larger house about a mile closer to the station. So far for the good news.

EPC scaleThe bad news is that our new-to-us 1970s detached house was rated E52 (on the UK’s scale of A100 to G1 for environmental performance) on the seller’s Environmental Performance Certificate. Fortunately it did have a full set of 2-year-old double glazing but not much else – including it turned out an arthritic boiler that couldn’t heat all the radiators but did manage to heat both expansion tanks in the loft.

So, over the last few months, we’ve been sorting out a few things to improve our environmental credentials and, at the same time, reduce the energy costs estimated at £2,114 per annum (£176 per month) on the EPC.

One of the first things we added was 4kW of solar panels on our south-south-east facing roof. That wouldn’t necessarily have been my first priority as autumn headed for winter, but with a reduction in the feed-in tariffs imminent it seemed sensible to act sooner rather than later. To get the highest feed-in tariff rate it turned out that I also needed a ‘D’ so I switched to low energy bulbs (worth 2 points), fitted the panels (worth 6 points), all of which should have got me 8 points so a D60 and then ordered a new survey..

The new survey came in as a C73 rather more than the D that I’d expected. Key highlights in the different surveys were:
o Walls – from 2 stars to 4 stars as the new survey found evidence of existing cavity wall fill,
o Windows – from 3 to 4 stars after I showed evidence of the installation date,
o Main heating controls – declined from 4 to 3 stars as only 2 TRVs found,
o Lighting – from 1 to 5 stars with all my new low energy bulbs.

Subsequently we sorted out the boiler and controls, so picking up the points values of the latest EPC:
o Hot water cylinder thermostat (as we went from gravity hot water to pumped) – 3 points
o Heating controls (TRVs) – 1 point
o Replace boiler with new condensing boiler – 7 points
o Solar water heating – 1 point

That latest list amounts to 12 points which should have got us from E52 to B85.

End of 2012 Gas Analysis

Well like many UK homes our central heating and hot water is fuelled by natural gas. We also use natural gas for cooking on the stove top (the oven is however electric) and we have a gas fire in the living room, but these latter two uses are much less significant.
I’d lived here for 10 years before I started actively trying to reduce my energy consumption. During those 10 years I used an average of 562 units of gas annually.
Since then I’ve reduced my consumption by two routes, firstly to reduce heat loss so that less energy for heating was required, and secondly by replacing gas with renewable sources. It’s however also the case that my circumstances have not been constant during that time so, for example, when I started this I lived alone then 4 years or so ago I married and my wife joined me here; and now my wife is at home during the day with our baby daughter much of the time. Consequently the demand for hot water for washing and heating has increased.
The steps taken to reduce gas consumption include:

  • Having insulation installed in the cavities of the house walls. Houses here conventionally have a double skin of brick or block and, when this house was built, the cavity between the inner and outer layers was usually left as an air gap. We’ve had that gap filled with insulation as you would find in newer homes.
  • Increasing the thickness of insulation in the loft.
  • Replacing the old wooden windows with new PVC ones with higher “A” grade insulation – most easily seen by the larger air gap in the sealed units.
  • Installing solar water heating panels on the roof in conjunction with a larger hot water tank. In the summer these provide almost all our hot water (no heating is required), although at olther times of the heat they don’t provide enough heat alone for hot water they can help to pre-heat the cold water leaving the gas less work to do to achieve a usuable temperature.

We didn’t do this all at once, but if I compare the last 2 years to the original 10 year baseline then we’ve reduced average annual gas consumption by 23%. I think that the reduction would have been higher had our circumstances between constant.

Well hello..

Hello out there.

This is for the moment something of an experiment as this is my first attempt at creating a blog, so polished it ain’t but hopefully it will get better over time.

Like many people I’m concerned about the state of our planet. It would seem that those of us in the west need to make some significant changes to our lifestyles to try and stop catastrophic damage to our world. Some reports talk of global warming wiping out whole countries and creating hundreds of millions of refugees. Something needs to be done. Someone needs to do something.

Then it occurred to me, here I sit in the UK in one of the world’s wealthiest countries. I have a well paid job, and a nice home. If I can’t change my lifestyle for the better, then who can be expected to?

So over the coming months I’m going to be logging some of the changes that I’ve made. Some are quite big, and others are quite small, but among them there will be something that everyone can do, because even the longest journey is made one step at a time.

Electricity

One of the easiest things that can be done to reduce the environmental impact of your home is to use renewable energy. You could of course buy your own wind turbine or cover the roof with photovoltaics, but those are both quite expensive and may not be appropriate for all homes. However that doesn’t stop you using renewable energy.Wind Turbine at Dagenham

You might not be able to make your own, but why not buy it from someone else? Just as you can shop around to buy cheaper electricity you can also shop around for greener electricity. A service like Simply Switch can quickly find you a greener electricity supplier, and depending on who you buy your power from now it won’t necessarily be any more expensive.