Keeping us out of hot water - the last notes on heating

Around 60 per cent of carbon dioxide emissions from a home are generated by one’s boiler, i.e., by central heating and the heating of hot water for taps and showers. According to the British Energy Saving Trust, simply changing boilers to high efficiency one can cut a house’s emissions by close to 900kg a year. If to that you add heating controls the savings will be about double that. Besides this, there are a few other things we can do to improve our house’s environmental performance. And many of these require only a small investment of money and time, or none at all.

This post goes briefly into a number of these simple things we are often just to distracted to get down to doing, or which never occurred us we should do. Since it is mostly a list of things, it is not very well structured, for which I apologise beforehand ^_^

To start, I’ve written quite a bit already about boilers and furnaces on the previous email but besides emphasising again how important it is to make sure you have a condensation boiler, both because of the emissions it saves and because of the money you will save in the medium-term, there are other things to also take into consideration when choosing a boiler and all that goes with it:

Combi or not

Traditional types of boilers worked with storage and expansion cylinders. The first type stores the water that gets used around the house and the second is really just a bit of space into which water can expand as it warms up in order to avoid increased pressure in the system, which could damage pipes and radiators. These tanks require a bit of space which in many houses comes at a premium, leading to the development of combination boilers .

Combination boilers heat up water instantaneously but only whenever hot water is necessary. So you avoid the need for tanks and never run out of water. This is often cheaper and easier to install and maintain. You do have to take care, however, to make sure the boiler you buy is able to provide you with the appropriate pressure and flow for your needs. There are options, however, which come with pumps and small tanks included within the boiler which are able to provide the water you need, when you need it and at the pressure you need, without requiring extra tanks and devices. In fact, anyone installing a heating system will be able to inform you and help you choose the appropriate condensation boiler for you needs.

Now, you might wonder if it makes a difference when it comes to energy usage and emissions.

The truth is that besides taking up less space, a combi boiler will actually also be a bit more efficient. In traditional boilers with storage tanks, the hot water just sits there until it gets used. If the water gets used right away, no problem. But if it stays there for hours, no matter how well insulated the cylinder is, there will always be a certain amount of heat that escapes, i.e., gets wasted. Since combination boilers, at most have a much smaller internal tank, this waste will be much or totally reduced.

Heating controls

The Energy Saving Trust (energysavingtrust.org.uk) mentions savings related to a correct setting of the house’s heating controls which run close to 1/5 of the energy usage. I can attest to having managed even better than that in my flat, even though I must admit I have some locational advantages (namely, sunshine throughout most of the day, set between floors, so I get a part of my heating for free).

The whole idea is to have the right amount of heat when necessary and to not have heat when it is not necessary.

To do this you will need a programmable timer and a thermostat (usually available as a single device), and a boiler with temperature controls.

Starting with the temperature of the tap water. A lot of people never even think of checking what temperature their boiler is heating up tap water. Unfortunately, very often the settings are set way too high at installation, which means if you set tap water to a lower temperature you will save energy. It can actually e more comfortable to do so, if the temperature was originally set so high that it burns the hands or dries the skin.

Also, the lower the temperature of the water that is sitting in the tanks and pipes, the lower the rate of heat loss, which means you cut down on wasted energy.

The other side of regulating temperature is setting the room temperature to a comfortable temperature (for most people between 17º and 21º Celsius, even if for some it make take a couple of weeks to get used to 21º as maximum because they have been setting the temperature at 23º or 24º up until now).

Of course, you need to set the timer to provide this range of temperatures when they are required. There is no point in having the house at 18º from 8am to 6pm if everyone is out at work. In this case you are better off leaving the heating off and letting the temperature fall. Then you set the timer to start heating 30 mins before you get back home and you will not notice a difference in comfort at all. You will, however, notice a difference in your energy bill, and the planet will be much better for it too.

So, to cut it short, set the temperature to 17º maximum during the night, set it to warm up a bit 30 minutes before you wake up, switch it off 30 minutes before you leave for work, and switch it back on 30 minutes before you come back.

Other ways of improving performance

Use insulating reflecting sheets behind the heaters. Heaters tend to be set against a wall. This means that a lot of the heat warms up the wall, and gets transmitted outside, instead of heating up the room. A very cheap solution for this is to get a roll of insulating reflecting sheet. I don’t know what the actual name for these things is but I’ll explain what it is and it should be easy enough to find in most cold countries at least. These sheets are basically polystyrene foam, or another insulating material, coated with a sheet of aluminium. The aluminium will reflect the heat from the heater back into the room and the polystyrene foam keeps the heat from actually getting to the wall where it would be wasted. I’ve seen official brochures from authorities claiming an improved efficiency of the heaters in the order of 30%.

These sheets are easy to install. You simply buy double-coated sticky tape, and stick them to the wall behind the radiator. They are also extremely cheap. I did the heaters in my whole flat for close to € 15.

Do not obstruct the top of the heaters. Heaters warm up but warming up the air around them. This hot air will go up because it is lighter than cold air. This will in turn suck cold air from lower down to replace the hot air that has gone up. This air will then itself heat up in contact with the radiator and move up and so on. If you keep things on the heater, or above it, this will keep the hot air from circulating freely, meaning the system will work poorly. Definitely avoid boxing in the heaters for aesthetic reasons. It will cost you and it will cause a lot more emissions.

One measure that can help improve your house’s performance is looking at the pressure you have in your taps and shower and see if you have the possibility of changing it. If you have high pressure at the taps and your installation allows for it, you can probably reduce this pressure without any effect of your comfort. Besides saving water, a small decrease in pressure will imply that you can save a reasonable amount of energy too because your boiler will have that much less water to warm up. Since reducing pressure reduces the amount of water more than proportionally, you can actually reduce water consumption and energy used to heat it up without it being all that perceptible to the end users of the house.

Another good measure is what they call bleeding the radiators from time to time. Some installations gather air in the pipes which make the circulation of water more difficult and decrease the efficiency of your installation. Bleeding should be done with the heating out and the radiators at maximum output. You simply open the valve at the end of the radiator and let the air out until it stops. Be careful because it may ‘spit’ a bit of dirty water at the end.

People who have tanks in their installation should insulate their tanks. The better the insulation the lower the useless loss of heat. Pretty straightforward. There is some advice on the appropriate thickness of the insulating jacket in several websites, such as the energy saving trust for example.

Insulating hot water pipes, especially between boiler and hot water cylinder (where the water is hottest), is another no-brainer, if you have the possibility to do so, i.e., if you are doing renovation work and the pipes are out in the open or if it is an old house with pipes not inserted into the wall. It might not be worth breaking open all of the walls simply to insulate the pipes though.

Not exactly related to central heating, but before I forget, there are, of course, other devices in the house warming up water, and these should also be object of attention when it comes to energy saving. Especially if you have a lot of warm drinks, remember to only boil as much water as you need (or the minimum required for the device, if your needs are below that minimum, of course). The amount of energy wasted through boiling too much water for tea just in Britain, for example, would suffice to supply the electricity needs of some small countries.

Also, when boiling water in a stove, or during cooking, keep the cover on the pot or pan you are using. As much as half of the energy will be escaping into the air otherwise.

And finally, that big consumer of hot water: the washing machine. Most clothes can, and are better off washed at 30º. But more than that, washing at 30º will save you close to half of the energy in comparison with higher temperatures

Heat your house, not the planet

Well, it took a while but, after one French and one German course, my holidays, a flu and the usual getting through the chaos accumulated during the summer recess, I’m back to finally follow up on the previous post about heating. The original plan was to get it online back in July, but never managed to really get around to it until now. But better late than never.

So, as I wrote before, the best way to save on heating is to find alternatives to it (see previous post). But that said, in most regions at least, a certain level of heating will still be desirable for a certain part of the year. If nothing else, one will want to have hot water for showering and washing. For most people this means choosing an appropriate boiler or furnace. Some might consider alternative systems such as electrical systems or geothermal heat pumps.

Lets start briefly with these two before moving to talking about the more common boiler and furnace based systems.

Electrical Systems
Heating up a house using electrical systems is usually pretty expensive. Even in countries where electricity is (still) relatively cheap, gas, oil, and coal will usually give you much more energy in terms of Kilowatts/hour for the same amount of money. There is at least one simple reason for this, namely, that when you get electricity you get energy which has already been processed, and every time you process something, you loose part of it. So, basically, when you pay for electricity, besides paying for the infrastructure to generate and transport the electricity, and the electricity you get, you also pay for the including the energy lost during this process of generating this electricity.
And, unlike what one might think, generating electricity wastes an enormous amount of the energy present in the fuel. A typical, run of the mill fossil-fuel fired power plant only spits out about 4 units of electricity for each 10 units of fuel energy it gobbles up. This number is probably an average, since newer plants burning gas, for example, will be much more efficient than an old design coal-fired plant. But you have to remember that it takes decades to replace this type of infrastructure and most of our electricity comes from traditional plants which were built 20 or 30 years ago, or at least have designs that old, and for which it the scope of efficiency improvements is limited.
Naturally, in such a case, even if you were to have a 100% efficient electrical heater, the overall efficiency of your heating will only be around 40%.
This compares to typical efficiencies for central heating above 90% for gas; 80-85% for oil-fired, and even 45-60% for coal-fired heating.
Add to this that some electrical devices used for heating are hardly efficient, with heating through air-conditioning systems probably rating worse of all.

Electrical heating makes sense, from an environmental point of view, only when you are able to generate your own electricity in a clean way, such as from wind, solar or hydro power. You can also contract a carbon-free electricity supply, but besides it probably being expensive to use for heating purposes, I figure since the supply of clean electricity is limited, that this will only mean that the green electricity you use will not be used elsewhere, leading to the generation of dirty electricity to cover that demand. But hey, that's my just my opinion.
And don’t get me wrong, I find contracting carbon-free electricity a great idea because it leads to further investment in wind, solar, hydro, etc.. But for heating, at least, there are better alternatives.

Geothermal heat pumps
If you have ever visited caves or mines, a guide might have mentioned at some point that the temperature down there is fairly constant, running at around 16° celsius or approximately 61° Fahrenheit. As it turns out, you don’t have to go into a mine for that. The temperature underground, from a depth of about 2,5 meters on does not vary much throughout the year or from place to place.

Geothermal heat pumps are systems that take advantage of this relatively high ground (and groundwater) temperature to heat up your house. Basically, a number of wells or trenches are dug, in which pipes are installed. A small pump circulates water through these pipes, which carries a part of this stored heat into your house, thus warming up your house.
Of course, most people would like their house to be slightly warmer than 16° Celsius (61°F), so a boiler is then used to make up the difference. Since the temperature differential will be much lower, of course, the boiler will only need to consume a fraction of the energy it would otherwise require to keep the house warm. The energy usage is as low as 30% that of a simple boiler setup.
On the down side, of course, the installation costs are high and it will take some time to payback. But it is, no doubt the cleanest method of central heating (except for carbon-free electrical, of course)

Gas and Oil Boilers and Furnaces
Heating accounts for around 60% of a house’s CO2 emissions (and a high percentage of the costs). Making the right choice of heating system is therefore paramount

First question, boiler or furnace? Well, according to the U.S. Department of Energy's ratings the most efficient systems are high efficiency furnaces. That said, however, the difference to one’s heating and environmental costs from having a high efficiency boiler or furnace is relatively marginal when compared to all the other variables that will affect the house’s energy efficiency.
Besides, matters of space and exact needs will weigh much more heavily on the choice.

Since I have no experience with furnaces I’m going to refer only to boilers.

The first question that comes to mind then, is whether it is best to choose a gas or an oil boiler. From an environmental point of view, gas is the cleanest of the options.

According to official data from Defra, the carbon content of domestic heating oil is running around 0,24Kg CO2 per kWh whereas gas is running at 0,19. I must admit I thought the difference would be higher but there you go.
On the other hand, I have found manufacturers claiming an improved burn efficiency for their latest models of oil boilers (as high as 95%), which would make them slightly more efficient than gas boilers. They claim that this compensates for part, though not all, of the extra emissions due to the higher carbon content of oil.
So, what may one conclude from this in my opinion? That oil-fired central heating has improved its performance quite dramatically. So, if you have no access to mains gas, a top range oil boiler will be a decent enough alternative.

But, if you have a choice, definitely choose gas.

Question 2: what type of boiler should I have?

In some countries, the choice has pretty much been taken off your hands because all the boilers sold must be high-efficiency condensing boilers. This is the most efficient boiler type, achieving efficiencies of over 90% (i.e., over 90% of the energy existing in the fuel gets transformed into heat) compared to efficiencies of only 70% for conventional boilers. Condensing boilers exist for both gas and oil.

The way they manage to achieve such high efficiencies is by removing heat from the exhaust or flue gases and feeding it back to the system. The flue gases are cooled down to a point where the water vapour in them condenses, releasing latent heat. This allows recovery of heat that would normally end up in the atmosphere, and therefore lower emissions of CO2 and NOX.

Externally, condensing boilers look pretty much the same as conventional boilers, and it is possible to fit them into most old heating systems. Which means that even if you already have a boiler, it is well worth considering getting it replaced by a new condensing boiler. Savings will be running around 30% both in terms of costs and of emissions, to which one might add the lower repair costs when compared to a decade old boiler.

Coal and wood
Just a word or two about coal and wood. Regarding coal, it is possibly the cheapest fuel in the market, but it is also the dirtiest and the least efficient. So, from an environmental point of view, both regarding CO2 emissions and toxic particles, it should not really be an option. A coal furnace is also about only half as efficient as an oil or gas one.
With the high fuel prices, some people have also started buying up those old iron heaters running on coal or wood. Some people might still have seen these in one’s grandmother’s house, or in antique shops. They do have a lot of charm, I’ll give them that, but they are hardly clean. So, if you have a choice, I’d say just keep them as decoration. ^_^

Another popular heating method is using fireplaces, though most people will probably use them more for ambiance than heat. The problem with fireplaces is that besides not burning in a clean manner, they generate an ascending draft up the chimney. This is great to carry the smoke out, but it is also great to carry the heat out. As warm air disappears up the chimney, cold air is going to be sucked into the house through every path available, of which there are always some, no matter how well insulated one’s house is. The end result is that, not only does your fireplace not heat the house properly, or even the room where it is, it might actually lose more heat than it generates. If you have central heating, this will force it to work harder. I.e., your fireplace might actually work against your central heating, instead of helping it keep you warm.