( CNN ) -- A group of architects gathered in Oxford , England last month with an unusual brief -- to design the ultimate dream home for bats . The winged mammals are valued from an ecological viewpoint for preying on insects , dispersing seeds and pollination . But their numbers have declined dramatically in North America , where a fungal disease called white nose syndrome is estimated to have killed more than 5.5 million . In the United Kingdom , the fungus has yet to appear , but habitat destruction remains a major threat . Policy-makers in the UK have stepped in to protect bat populations , criminalizing any interference with their roosts , even if no bats are currently present . `` If you have bats roosting in your building , you ca n't disturb them in any way without getting a special license , '' says Kelly Gunnell , Built Environment Officer with the Bat Conservation Trust , a charitable organization in London , England . Those who interfere with a roost risk a fine of $ 7,800 per bat , and up to six months in prison -- although Gunnell says no one has been sent to prison yet . The new , three-hour course , offered by the Royal Institute of British Architects in conjunction with the Bat Conservation Trust , is intended to educate architects about bats , teaching participants the ideal size , access points , temperature , materials and location for bat roosts . `` They need to design these spaces which are biodiversity-friendly , but they 're not ecologists , '' explains Gunnell . `` This gives them a basic introduction to their life cycle , when they breed , and their requirements for roosting . '' Bats prefer to roost in natural features like trees and caves , but as development has made those environments scarcer , some species have adapted to urban areas . `` Only about half the bats here regularly use buildings as roosts , although nearly all of them will use them at some stage , '' says Gunnell . `` Unfortunately , with a lot of people doing loft conversions and barn conversions , that 's had a huge impact . Bats only have one young a year , and they do n't have them every year , so if they were using your roof loft as their maternity roost and you knocked down the building or put in a loft extension , it would wipe out that whole population . '' Research ship finds the world 's oceans are 'plasticized ' Bats present several logistical challenges for designers . English bats are tiny , with the smallest species , the pipistrelle , able to fit into a matchbox . `` They can squeeze into the smallest places , '' says Gunnell . `` Literally , if you can put your finger into a gap , a bat can get in there . '' They have varying space requirements . Some species prefer tight spaces like cavities under roof piles , others need more space , like that found in attics . All bats need darkness and warmth . A problem for both builders and bat conservationists is the widespread use in modern buildings of `` breathable roofing membranes '' , a type of insulating textile which allows air vapor to escape . Roosting bats can get fatally entangled in the fibers , which degrades the roofing membranes , invalidating their guarantees . Solar panels present another issue . `` It 's very preliminary , but there seems to be evidence that when you put solar panels on your roof , it can increase the internal roof void temperature , which can be disturbing to bats , '' says Gunnell . Charles Barclay , who has an architecture practice in South London , has built a bespoke bat barn that was shortlisted for a sustainability award by the British Architect 's Journal last year . Wine turbine creates water from thin air . While demolishing a 100-year-old brick farmhouse in Suffolk , England , a maternity roost for brown long-eared bats was found in the attic . This meant Barclay had to provide a new roost , which took six weeks more than $ 70,000 to complete . His design incorporates a downward-angled port where bats can enter , leading to a 34mm-wide chute with roughened timber walls which they can crawl up to gain access to an attic 10.5m long and 3m high at the apex . Once the barn was finished , the sleeping bats were put into a soft bag by an ecology consultant , and delivered to awaken in their new home . `` He also transferred their droppings , so they could smell a bat-friendly area , '' Barclay says . Although the Suffolk bats appear to have taken up residence , Gunnell says there 's never any guarantee that such solutions will work . `` The problem we have is that , even if you take everything into account for the bats , they often just wo n't use the space you 've created , '' says Gunnell . `` Or , if they do , it can take them up to five years . '' She continued : `` A few years ago we had a bat house design competition . They got architects involved and built a bat house at the London Wetlands Centre . That 's quite a nicely designed bat house , but two years on , it 's never been used by bats . Sometimes you can do everything absolutely right , and it still wo n't be used . ''
A new course aims to teach architects how to accommodate bats . UK legislation protects bats and their roosts , with fines and jail time for offenders . Bats can get tangled in some modern roofing insulation . Some English bats are small enough to fit into a matchbox .