London ( CNN ) -- In five years time , all new homes built in the UK will be required to be zero carbon , with no net carbon emissions over a year . CNN spoke to green house-builders and environmentalists to answer some burning questions about zero carbon homes . Why do we need zero carbon homes ? Some 26 % of UK 's carbon emissions come from homes , making it a significant area for reducing emissions overall , according to UK Green Building Council and WWF . Neil Jefferson , of the Zero Carbon Hub , the agency set up by the British government to help achieve its target , said an average home built in 2006 emits 3.2 tons of carbon a year and a typical 100-year-old home emits about six tons . By 2016 , all new homes will have zero carbon emissions over a year . This will be a minimum requirement for homes to gain planning permission . Of course , most people will not be living in new houses , so existing homes will also need to be made more energy efficient , according to Zoe Leader , sustainable homes policy adviser for WWF . The UK aims to build somewhere in the region of 200,000 new homes a year , a drop in the ocean compared to more than 22 million existing homes . Quiz : Do you live a sustainable life ? What exactly does zero carbon mean ? Zero carbon homes will have no net carbon emissions over the course of a year . Energy use will be minimized by use of thermally efficient building materials and insulation . All the energy used to heat and light the home and run its appliances will need to be off-set using zero carbon technology such as wind turbines , solar panels and ground source heat pumps . When the target was originally set in 2006 , it was envisaged that all this renewable energy would be generated onsite , according to Jefferson . However , following a report in 2008 , which took in views from industry and green groups , it was decided that to be realistic , the definition needed to be relaxed to allow contributions to off-site renewable energy schemes . This would allow house-builders to make payments into new community energy schemes to off-set the carbon emissions of their homes . The exact definition of these `` allowable solutions '' as the off-site schemes are known , is still being worked out . Leader , of WWF , said : `` We need to make sure these allowable solutions are truly additional , and not things that would have happened anyway . '' The UK has a Code for Sustainable Homes , where the highest level 6 is zero carbon . Regulations will require homes to move gradually up the scale before 2016 . How does the UK 's target compare with others worldwide ? Jefferson , of the Zero Carbon Hub , said : `` The target is without doubt the most challenging in the world . '' Many believe that while countries such as Germany , Sweden and China have already produced more zero carbon homes than the UK , nowhere else can rival its ambitious target for 2016 . John Alker , director of policy and communications at UK Green Building Council , an industry body liaising with the government over green issues , said : `` This country 's target is world-leading , not on what we have delivered so far , but in ambition . `` EU legislation is leading towards zero carbon building , but the UK is ahead of the picture in having such an ambitious target . Germany and Scandinavia have historically had better building standards and some countries have decided to tackle the commercial building stock first . '' Leader agreed : `` There are pockets of sustainable developments such as Freiburg in Germany and Malmo in Sweden , but nowhere else has a far-reaching policy like this . `` EU legislation is heading toward zero carbon building by 2020 . '' However , Bill Dunster , an architect who founded ZED Factory , based in the UK and China , and has built between 300 and 500 zero carbon homes worldwide , said : `` There 's very little demand in the UK compared with Germany and China , who are both far more ambitious and innovative . '' How many zero carbon homes have been built so far ? Very few . In 2007 the UK government announced tax relief on zero carbon homes and so far only about 25 homes have qualified , according to Alker , of the UK Green Building Council . However , this tax relief was based on the definition that all off-set energy had to be produced onsite , a definition which has since been considered unrealistic . Alker added : `` This is a future policy and standards are ramping up between now and 2016 . There 's not a huge incentive to go out and do it now . '' Dunster , who founded ZED Factory in 1998 , said : `` Despite what all the volume house builders are saying , it 's not difficult if you want to do it . We are just getting on with it . '' He added : `` In the UK , we are doing small-scale privately funded developments , whereas in China we are being asked to design whole city extensions with thousands of homes . ''
UK regulations will require all new homes to have zero net carbon emissions by 2016 . Comment: Germany , Sweden and China have built more sustainable homes so far , say environmentalists .