By Vladislav Velev
Darik Radio reporter, Sofia
Bulgaria's communist-era power stations rely on Russian gas
Millions of Bulgarians now live in colder homes because the shutdown of Russian gas supplies has hit the country's centralised municipal heating.
In communist times Bulgarians could always rely on gas from their giant Soviet neighbour. They cannot recall a time like this, when such a vital energy source was missing.
Adding to the misery, temperatures have plunged well below zero.
The gas shortage means colder radiators, because there is less power to heat water to the correct temperature.
"I feel almost desperate," says Virginia Boiadzhieva, mother of a three-year-old boy in the capital Sofia.
"The central heating is the only way we could warm our apartment - the centrally delivered hot water is the only option for us.
"If the heating goes we could use a fan heater - although it would be more expensive. But if the hot water stops we'll have to stay with my husband's parents. They have an electrically-powered boiler, but we don't."
Prime Minister Sergei Stanishev admits Bulgaria is facing a serious energy crisis, as it depends almost entirely on Russian gas.
The first to feel the impact were factories and municipal heating centres, which now have to switch to using diesel. But that takes about three days - so customers in the cities are feeling the chill.
Seventy-two schools in Bulgaria, reliant on gas-powered heating, were closed on Wednesday.
Energy Minister Petar Dimitrov has warned that the power system may not be able to cope with the extra demand for electricity.
Meanwhile the Mayor of Sofia, Boiko Borisov, has urged people to save electricity. "It's not about a lack of electricity, but if we start heating with it, Sofia's energy system will not be able to bear such a surge and the whole system will collapse," he warned.
At an emergency meeting on Tuesday Mr Borisov ordered a temporary switch-off of the decorative lighting on some of Sofia's buildings.
Bulgaria has some gas reserves, but they are not enough to keep the economy and ordinary life running smoothly for a long time.
Some of the biggest factories - like the brewery in Plovdiv and four bakeries in Varna - have had to close due to the lack of gas.
Bulgaria's plants are collectively losing at least 500m lev (£234m; $344m) daily because of the gas cut, according to Evgeni Ivanov, head of the Bulgarian Confederation of Employers and Industrialists.
Some elderly Bulgarians have turned off their heating altogether because they cannot afford to pay for it.
"Cold. Switch on the nuclear plant!" says this newspaper headline
One such is 73-year-old Snehza, who said: "I've been living in a cold apartment for three years - I don't see any difference now.
"I don't have central heating. I just put on as many clothes as possible and when it gets extremely cold I switch on an electric heater for a while."
On Tuesday President Georgi Parvanov suggested restarting the third reactor at the Kozloduy nuclear power plant, to help Bulgaria deal with the crisis.
But that - even if it were allowed by the EU - would take at least a month to put into effect. Bulgaria had to close two reactors on safety grounds, as part of its EU accession conditions.
Energy minister Dimitrov told Darik Radio that Bulgaria was still exporting electricity, so the country "couldn't say that it's in such a critical situation that it had to restart the reactors".
Service sectors hit by the gas shortage include taxi drivers, who say they might stop work as many of their cars run on methane, which is not available now.
Bakers have warned that within days the bread price could rise by at least 5% because they use gas-powered ovens.
Minister Dimitrov says the crisis is huge but "should be resolved within days". Many people enduring freezing cold in unheated homes may not share his optimism, however.