Just how smart are smart homes?

When I first lived in Tokyo in the mid 1980's I remember being out somewhere and a friend got up to use the telephone. It was a payphone since this was before the age of mobiles. He didn't say anything, but punched in some numbers then put the phone down. He told us he'd just started the bath running at home.

If you don't know what a payphone is,
you probably won't know what this is either

This seemed like science fiction to me with my perspective from the primitive plumbing of England. Indeed it was science fiction compared to the Tokyo flat I was staying in where there was no running hot water, and the bath had to be filled with cold water, then heated by circulating water through a gas burner. Once, after a long day, I got into one such bath while the heater was still on. I dozed off in the bath and woke up very hot, and when I moved I got even hotter since I had been cooling the water immediately around me.

Most bath heaters had simple mechanical timers in the switches, so they would not overheat the bath. Even in the 1980s some of them could be programmed to switch on at a certain time, so the tub would be hot when you got home.

We can't call our bath on the phone, or send it text messages, but it can be programmed to come on at a certain time, and it does know how to say "I'm filling up the bath" and will happily tell us "The bath's ready". Unfortunately it doesn't know how to say "Whoops, I ran out of water so your bath is luke warm." And the phrase, "Hey, you forgot to put the plug in, you idiot" is also missing from its vocabulary. In both cases, the light just goes off and it remains silent. It's really not very smart.

So how smart are smart houses? Not very, is the short answer. Will they help us to save energy? Our bath could have saved us a few hundred litres of hot water if it just knew to tell us that it wasn't filling up and we'd left the plug out. So excuse me if I'm skeptical of the age of the smart house and the brighter future offered us by the internet of things.

If you want energy efficiency, then it is dumb things that will deliver: geometry, wall thickness, window quality, airtightness and attention to detail in the construction.

You can get gadgets if you want, and they may make your life better, but if you want to save energy start with the thermal envelope. You can stick as much as you like onto the envelope later. This applies to solar panels too, which are probably a good idea to add to your house, but they will not make your house more energy efficient. Putting insulation under the roof is a much higher priority than putting solar panels on top of it.

But don't just take my word for it. In Bringing users into building energy performance: Learning to live in a smart home, Tom Hargreaves, Charlie Wilson & Richard Hauxwell-Baldwin tell us that smart home devices are "technically and socially disruptive", are limited by the householder who is using them, and have a steep learning curve with few people to help you climb it. They also find "little evidence that smart home technologies will generate substantial energy savings and, indeed, there is a risk that they may generate forms of energy intensification."

The coffee maker question

The teachers' room has a coffee maker. Usually five days a week, twice a day, someone makes coffee in the break time, has one cup, then the rest of the coffee sits in the pot, with the heater on, for 90 minutes until the next lesson has finished. 

The coffee maker uses a 1 kW heating element to keep the coffee warm.

There is a new coffee machine with a thermos flask pot, and no heating element.

It costs 10,000 yen.

Electricity costs 25 yen per kWh

If we buy the new coffee machine, how many weeks will it take to save the money?

Getting the least out of your fridge

When we go to the local electrical store, especially to buy something, I'll often start asking questions about the design or manufacture of their products. This will usually result in blank faces or repetition of advertising dogma from the sales rep, and a kick from my better half, with a suggestion that I write to someone in the company rather than bothering the staff.

This happened when we recently went to get a new fridge. Our old fridge was thawing and on its last legs. Probably the compressor going. I suppose we could have got it fixed, but it wasn't a very good fridge to start with. They had replaced it for our old fridge, which had had problems with the ice maker, but the replacement never seemed very satisfactory. It was about ten years since we bought a fridge, and I was expecting a few quantum leaps in the technology, but the main evidence was for incremental improvements in insulation and compressor efficiency. Fridges are major domestic electricity users (10-20%), and the improved efficiency probably makes the new fridge worth it, at least in economic terms. The sales staff in the electrical shop were certainly enthusiastic to tell us this. Evidence from Kakaku.com suggests three times less energy use between 2003 and 2013 models in Japan. And here's a graph showing electricity consumption of fridges in the US rising from their mass production in 1940s to a peak in the 1970s to a return to 1940s consumption around 2002, at a much larger size and for less money. (The flat part corresponds almost exactly to Bill Clinton's presidency, which may just be a coincidence.)

I had expected fridges to get a bit more intelligent. There has been some talk of smart grids, and now many houses are loaded with solar panels, which they were trying to sell in the very same shop. I expected the noble fridge, leader of the white goods, would be rising to this challenge by making more coolth when power is available, and using less power when it is not.

Blank faces.

Another question: why is the door for the fridge the same thickness as the door for the freezer? It's colder in the freezer, so wouldn't it make sense to have a thicker door with higher insulation?

More blank faces.

My answer to that question would be that it makes manufacturing easier, and fridges cheaper.

This article from Proud Green Home has some useful information on buying and using low energy fridges. It points out that smaller fridges use less energy, and that fridges full of food, or even bottles of water, will have less air to escape when the door opens and they will be much more efficient. This is in contrast to what the people in the electrical shops say: don't fill your fridge too full or the air will not be able to circulate and it won't cool your food properly. 

Why would they say such a thing?

Perhaps because they want you to spend more money on a bigger fridge!

Not only do smaller fridges use less power, they also contain less food. A significant proportion of bought food is thrown away uneaten, so unless you are able to guarantee none of your food is wasted, a bigger fridge probably just means you are going to throw away more food.

One technical development they seemed pleased with in the shop was a sensor inside the fridge looking at how cold things were. I don't understand how much of an improvement this is over a thermostat unless you are putting hot pans in there. As long as the insulation layer around the fridge is good, and heat is being pumped out, the temperature inside is going to be uniform soon after the door closes.  I will further investigate exactly what the control circuitry of the fridge is doing and what the green light on the door means.

The article also makes some interesting comparisons between different configurations. French doors would seem to be more efficient since you only need to open one door at a time, and therefore only lose half the cold air. However people often open both doors, and the doors may in fact be open longer as you are trying to remember which side of the fridge you left whatever you're looking for.

Also they show how more doors and more complicated configurations basically mean more heat loss. This will be no surprise to anyone who has been paying attention to my posts about thermal bridges. They point out that any fridge with ice and water going through the door will be less efficient than any fridge that doesn't do that. (Compare and contrast with the world's first passive house cat flap.) So if you're choosing for energy efficiency, they recommend getting one with a freezer at the top and no cat flap for water or ice.

Of course different countries have different shapes and sizes of fridge preference. Another question I had for the long-suffering sales rep was why their shop only had Japan-made fridges. A little searching on the web reveals that about the only universal in the global fridge market is that different markets favour products from different countries.

Advice on dishwasher connection running hot and cold

When we were planning the kitchen, we were advised to plumb cold water into the dishwasher. I think the reason given was that if the dishwasher is in control of its own water heating, then it will be at the right temperature. Domestic hot water was going to start off cold until water from the boiler got through the pipes, and this would upset the wash.

Meanwhile, the Japanese manual we have for the dishwasher announces that you can save energy by connecting hot water rather than cold water, since the dishwasher uses electricity to heat water, and electricity is a very expensive way of producing heat.

At the one (and a half) year inspection last year, one of our questions was about the dishwasher plumbing, and the builder came out with the same story we'd heard at the beginning: that the domestic hot water may be cold when it is first turned on as it goes through the pipes.

Further discussion with the Japanese suppliers of the German-made dishwasher confirmed this. Also, rinsing with cold water first is apparently better for removing proteins, like egg, which can be baked on with hot water and become more difficult to remove. So plumbing cold water allows the dishwasher to use both hot and cold water, but if you plumb in hot water, it can only use hot water.

There is a range of forum discussions online discussing whether to plumb dishwashers with hot or cold water, which seem to veer towards the side of cold water and leaving the dishwasher to deal with the heating, unless you're getting your hot water from a solar thermal system, in which case the hot water is effectively free.

But our hot water is not solar thermal, and even though the domestic hot water would save some electricity, and some cost since it's using night time rates rather than evening rates, so it doesn't represent free heat. The water is still using some electricity, probably more efficiently, but by the time it's lost heat waiting in the boiler to be used, lost heat in the pipes on the way to the dishwasher, been used when the dishwasher would rather have been using cold water, and possibly been further heated, then the saving is really marginal.

So once again, we're counting the number of angels that can dance on a pin head.