From an environmental point of view, electric heating of both space and water is quite tricky to get to grips with and depends partly on your point of view of the likely or desirable future energy generation mix in the UK.
Wasteful and inefficient
On the one hand there is the argument that electrical energy is highly wasteful in terms of generation and distribution through the grid. Only about a third of the energy which oil, gas, biomass or coal contain actually gets to the house. The rest is lost mainly at the power station but also in the national grid. There is also the fact that power stations cannot be switched on and off very quickly to cope with varying demand so they have to be run at higher output than is required most of the time.
All of this is why the price of electricity per kWhkilowatt hour. This is a unit to measure an amount of energy. If you run your 30 kW gas boiler for 2 hours a day you use 60 kWh per day is usually about 3 times the price of, say, gas.
This is all made worse by the way the UK, unlike several other European nations, has almost completely ignored large scale CHP Combined heat and power - where the heat which is produced when electricity is generated is used within a heating system rather than wasted. This can happen at different levels - within a single house, a housing development, a town etc. . Nearly all our power stations are remote from the areas they serve so their waste heat cannot be used for district heating. (a notable exception is the London borough of Merton)
Electric light good (beats gas lamps)!
It is an accepted fact that electricity is pretty much the only way to power lighting and most of what are called ‘electrical goods’ and there is a good arguement that it should be reserved for that kind of use rather than heating.
So when it comes to heating, it is much more efficient and environmentally friendly if a fuel such as gas or wood is burned where the heat is needed – within the house rather than remotely at a power station. In the case of the latest gas boilers over 90% efficiency can be achieved and wood pellet stoves are not far behind.
Having said that there are occasions when electric heating may make sense, especially if it is in the context of driving ground source heat pumps in areas where mains gas is not available. Indeed the PassivhausSee more on the Passivhaus standard. The PassivHaus Institute has pioneered a standard for low energy buildings. It includes very low energy usage and ways of achieving this. The word is derived from the idea of buildings which are fundamentally low energy and passive solar heated rather than using extra gadgets to heat them. See Passivhaus for the UK branch of the organisation. type of design may use very small electrically driven ground source heat pumps as their main source of heating (with the heat being introduced into the incoming ventilation air in the house). The heat pump may also heat the domestic hot water, along with solar panels.
Kissing good bye to fossil fuel
In the medium term the more fundamental aspect of the discussion may concern the likelihood of wind generation and nuclear power taking over from fossil fuel as the means of generating the nation’s electricity. If you believe, as for instance Lovelock does that we are already much too far down the road of the burning of fossil fuels and that the main practicable short term alternative to hand is wind, tidal/wave along with better nuclear, then heating by electricity and GSHPground source heat pump. A heat pump which extracts heat from the ground becomes a better option than fossil fuel. The exception might be the (very clean) burning of wood chips or pellets in a stove. The jury (if there is one) is still out on this one. The only certainty is that the better insulated a house, the less of a problem there is. For instance if a house is built to Passivhaus standard then no central heating system is required. This means a massive saving on fuel bills.