This is a work that look at the factors that affect future monthly costs when buying a house in Sweden and which options are the most financially favorable over a 30 year period. The work also examines whether it is economically beneficial to invest in a low-energy house regardless of geographic location in Sweden, and discuss about whether a calculation template can help individuals to choose more environmentally friendly options. The work has been limited so that a certain number of predetermined factors and its measurable values have been developed with the help of a literature study. The factors chosen are building type, climate, heating systems, loan interest rates, energy prices, energy price increases, inflation rates and down payment. These are then combined into 72 different calculation cases which get put in a calculation model made in excel. The model has a simple structure that can be used by most people, and based on these calculations we obtain the result. The result is shown as 72st month cost of a table, the results showed that the most profitable option in each climate zone where with the use of the traditional house. The three most expensive calculation cases for each climate zone were also with the use of the traditional house. The majority of the cheapest calculation cases when using the pellet boiler was represented by calculation cases with the traditional house and the calculations with the use of the oil-fired boiler, the majority were low-energy houses. Note that some exceptional cases existed. Every individual is unique and create different conditions for their monthly payments on their homes. This makes the factors affecting the monthly costs a large number. From this work it can be concluded that it is not economical to invest in a low-energy house under certain conditions. One can also see that the costs related to loans and heating are two leading factors of the monthly payment, with low loan costs comes higher costs for heating and higher loan costs results in lower costs for heating. The calculation template can favor and help people to find the most profitable option for their case, whether it is environmentally friendly or not depends on the conditions. To encourage producers and consumers to invest in sustainable alternatives the suggestion is to subsidize money to companies that build according to some sort of certification, this can result in lower prices for the more environmentally friendly low-energy houses.