Bulgaria's four biggest cities - Sofia, Plovdiv, Varna and Bourgas - have see a significant shift in the trends of the real estate sector, in particular the growing interest in property rental, data from real estate agency Address showed on November 24.The double digit increase on the market in 2008 has been credited to the sharp demand of property rentals, as a consequence of the global financial crisis and the subsequent decline in demand for purchase of single family homes, flats or planned unit developments.Address Real Estate's research showed that between January and October, the major trend in the real estate market was shifting towards rentals, observing a significant growth of 12 per cent in the market for the last three quarters.The largest interest is aimed at two-room flats, where the demand has increased by over 14 per cent, which has come at the expense for single-room flats or studios, which have registered a cooling off with a six per cent drop in demand, mainly because rental prices were very close to those charged for two-room apartments.Three-room flats are also on the up, recording a three per cent raise.Nationwide, amongst the four largest cities in Bulgaria, in the port town of Varna the increase has been the steepest, followed by Sofia, Plovdiv and Bourgas, Address Real Estate said, as quoted by Focus news agency.Rental demand in Varna was 13 per cent on the up for the first three quarters. compared to the eight per cent figure recorded in Sofia. The biggest demand in the capital is gravitating towards the Sofia centre, and the neighbourhood of Lozenetz, as well as the large residential boroughs of Mladost and Lulin.Bourgas rated last in the table with 5.43 per cent increase, the cheapest rate of all major towns in Bulgaria.The data showed that prospective clients were generally unconcerned whether the flat was in a newly constructed building or in a relatively old one. The main factors in making their decision is whether the flat has undergone recent refurbishment and whether it has the necessary appliances. Tenants generally are reluctant to be burdened with refurbishing the flat themselves, whereas prospective buyers are keen on making the choices themselves and having the flat built custom.Fully-furnished apartments are generally of older construction and on average command higher prices. New construction on the other hand, is exactly that - brand-new flats with no furniture or electric appliances.