Good morning, and welcome to the First Quarter of 2023 for Wallenstam. My name is Susann Linde. I'm CFO and Head of Investor Relations here at Wallenstam. If you have any questions, please click on the envelope on this page, or you can call me, or otherwise, you can join our Q&A session on the Swedish call, where Hans also will attend to the question session. Now turn to page two. The headline for this quarter is good position even in more uncertain times. We are a company that keep to our long-term strategies and do what we think is the best for the future and the development for our business. This is one reason why we have such a good position right now when we are in uncertain times.
These strategies are reflected in many things, for example, where we have our properties, what kind of properties, and how we are financed. Now turn to page three. The first strategy is where we have our properties. We want to have them in attractive locations where you both want to live and work. We are focused in Gothenburg and Stockholm and haven't changed that strategy since the beginning of the 90s. We have a total occupancy rate of 96%. In contrast, the concentration of the location of the properties, we think the opposite in terms of property type. Now turn to page four. We have a mix of premises in our portfolio, not just commercials or residentials. As many of you know, about 50% of the rental value consists of residential income, and the rest is commercial and then mainly offices.
To the right, you can see the distribution of the market value, where 55% are residential properties and 42% commercial properties and 3% properties for public use. We think this is a good mix that gives an overall good risk profile. They help each other during the different market situations. Turn to page five. We kept to our strategy to mainly finance our business with bank loans, this is something that we stuck to even though it hasn't been the cheapest. Again, in the long term, it is the safest for the company. To keep to these strategies, we also have chosen to refrain from rating. A rating model doesn't like secured bank loans in majority, for example. That is one reason that we can be flexible in our way of financing.
The bank loans amount to 95% of the loan portfolio, and the rest, 5%, is both commercial paper and bonds. What we did during the quarter is to further increase bank loans and decrease against the capital market, as you can see in the table to the left. We haven't been active in the bond market or at all and not just a little bit on the CP market. The banks feel positive and a good partner during this period. Regarding the bonds, SEK 460 million expires in August this year, and the rest in 2024. Turn to page six. The biggest expense in our operation is the interest. We secured a lot interest rate early last year, and now we have an average fixed interest rate term of three and a half year.
We haven't done any new derivatives during this quarter. 58% of the loan volume has fixed interest, which means a change in the interest rate by 50 points affect the interest by approximately SEK 60 million on a yearly basis. Next page seven. We haven't started any new projects this quarter, which is a shame when the demand of new apartments is huge. In our own queue, we have more than 240,000. Hopefully, we can start some projects during the year. We have 1,622 apartments under construction right now, and I will tell you the current status in some of them. Now turn to page eight. We begin in Mölndals Fabriker with a block, Skogsvaktaren, which we have occupied now in Q2. In this picture, it is almost completed.
It's in our urban development project, Mölndals Fabriker, where we have around 530 apartments now, with this included, in our own management. They are completed. Turn to page nine. We stay in Gothenburg, but we move to Kallebäcks Terrasser, our second urban development project here. Quarter six in Kallebäck was started last year and the entrance to this area. You can see to the right how it will look like when it's completed. To the left, you can see in the red square, how it looks like today. We have started to put up frames for the first building, and the occupation will start in 2025. Around these projects, you can see the other projects under construction, and some of them totally completed, just over 600 completed apartments. This is also a popular area like Mölndals Fabriker.
Now turn to page 10. In a very good location, you have this commercial property on Stampgatan in Gothenburg, close to the Central Station. The old tired facade will be changed. Now the work has started to build the 1.5 floors on top of the existing building. We will also change the energy system in this property. Convendum will rent 4,300 square meter here in this property when it's completed in the beginning of next year. We turn to page 11. In Stockholm, we started this project last year, Nacka Grace in Nacka. The work with the foundation is completed. There weeks ago, we started to put up the frames. The occupation will start in 2024 and will be fully completed in 2025. Also a nice project. Now turn to page 12.
Our project in Älta Torg Kv. 1 in Nacka is that the work with the foundation is completed, and also in this project, we have started to put up the frame. After the summer, the interior work will start. The occupation will start in 2024. Turn to next page. Page 13. Let us take a look at how our net operating income has developed. It's basically at the same level as last year, as you see here. It's just SEK 3 million. As usual, I want to go through what affected the different parts of net operating income on next page. Please turn to page 14. If we start with rental income, it increased by about 7% compared to the previous year, which is SEK 44 million. Our new construction that has been completed has a positive impact of SEK 27 million.
The acquisitions and sales we made last year, including the properties we vacated on November 1st last year, have a negative impact on rental income of around SEK 13 million. In the comparable holdings, the base rent has increased by 3.1% for residential and 8.3% for commercial. We have also recognized the second electricity subsidy for November and December of SEK 2 million, which we will pay out now to the residential tenants with sub-metering. Our operating expenses increased by SEK 40 million, and if you want to sum it up, it's mainly due to higher electricity prices of SEK 34 million. We will see further down in the income statement that this is met on the total where we include our wind power operations since we are self-sufficient in renewable energy. Otherwise, it can be said that this is mainly tariff increases.
Totally SEK 4 million up. Turn to page 15. The properties that we completed during the quarter are 108 apartments in block eight in Kallebäck, and there we have 158 apartments left to complete. We also completed our project on Djurgårdsgatan in Gothenburg, in which we converted premises on the ground floor into 14 new apartments. We turn to page 16. If we continue with the income statement and look at our income from property management, there is a decrease of approximately SEK 16 million compared to last year. In total, it can be said that this decrease is due to higher financial expenses due to higher market interest rates, such as STIBOR increase, which has increased by 66 basis points since the start of the year.
We have an average interest rate on closing day of 2.61%, and during the period of 2.41%, which is double the previous year. We also have a higher debt compared to last year of SEK 1.5 billion. Now turn to page 17. The net operating income from wind power is SEK 30 million higher than last year, and you can see that on other income and other expenses and financial expenses, other. That's the result of energy. The selling we made in June last year of 13 turbines means that we lose production compared with the previous year, which is in money about SEK 25 million. Now turn to next page 18. We come to the changes in value, and the changes in value of investment properties for the quarter are reported at zero.
We keep to the residential an average of a required yield of three and a half percent and commercial 4.6%. We continue to have a risk premium on our ongoing projects. When it comes to the transaction market, it's relatively quiet, so it's difficult to have comparable objects. Thus, the yield requirements are at the same since the start of the year, as I said. However, long-term interest rates have fallen slightly, which has negative impact on derivatives by approximately SEK 260 million. Profit after tax just around SEK 50 million. Turn to next page 19. We go to the balance sheet and start with the properties.
We have properties for approximately SEK 63 billion, of these, SEK 56 billion are properties that are in operation, the remaining SEK 6 billion are properties that are either under construction or land for future construction. On the next page, we see the investment volume for the year. Turn to page 20. We have invested a total of SEK 650 million during this quarter, that is approximately the same as it looked in the first quarter last year. Turn to page 21. Our interest-bearing liabilities amount to SEK 28 billion, which is at the same level as at year-end, like I said earlier, it's half a billion higher than the first quarter last year, so SEK 28.3 billion. Turn to page 22. A short summary with the help of some key ratios.
NOI is on the same level as last year, but the surplus ratio are negatively affected by higher energy prices and is recognized at 70%. The average interest rate on closing day is 2.61, and the ECR rolling 12 months is 4.1x . We keep our strong financial position with an LTV of 45% and an equity ratio of 47%. We bought some of our own shares in this first quarter. It was 500,000 shares, which means we have a total volume of repurchased shares of 1.5 million shares. The equity per share and the NAV has gone down by around SEK 1 since last year.
With this slide, it was all from today, and please contact me, like I said in the beginning, if you have any questions. Thank you for listening, and have a nice day.