What do you mean, you want a zero carbon building?!
You might think it is going to be difficult to get to zero carbon, but technically it can be done quite easily.
The right mix of insulations, managing passive solar gain, heat recovery and renewable energy will do it.
But, pause a little, let’s first examine what is really meant by zero carbon. Why zero and when will it be achieved?
A few facts to bear in mind:
A typical UK home uses 3300 kWh of electricity and around 16,500 kWh of gas (figures from OFGEM).
Based on average grid electricity using natural gas this results in 1650 kg CO2 from the generation of electricity and 3135 kg CO2 from the burning of gas. These are very high figures and we need to do reduce them.
In fact, the UK’s aim is to reduce all CO2 emissions by 80% by 2050.
The ‘roadmap’ shows we need a mix of energy efficiency measures and more zero or low-carbon energy sources. In everyday language, use less and what you must use needs to be cleaner.
So, to be zero carbon today we need to do two things to a home:
1. Use less energy in the building (and what you do use should be from renewables if at all possible).
There are plenty of examples in operation, usually using solar PV for electricity but some use a small wind turbine and a few benefit from locally generated small hydro power.
2. Buy the best low energy appliances. 
Looking at typical house figures shows that reducing heating needs to near zero (a passive house) would cut away 60% of CO2 emissions.
It might not be a zero carbon building but it you will get to a 60% reduction! Now, if in the next 40 years grid electricity halves in carbon intensity, then you get to an 82% reduction – which is what we need. Problem solved! (Oh no! What about transport, food, industry……..?)
