Great question, @getonthetrain, thank you!

No ongoing expenses whatsoever. My electricity costs are included in the monthly rent, at a flat rate (that is, independent of the actual amount of electricity consumed). Thus, for the purpose of mining profitability calculations, earnings = profit. If it wasn’t for this particular circumstance – plus a bunch of other favourable factors, such as: the low price of the miner I found on eBay, no sales tax since the seller too was in the EU, no external PSU required, since the miner comes with two built-in ones, plus the cold Swedish winter that helps to keep the miner and the apartment cool – I probably wouldn’t have started mining at home in the first place.