A geothermal heat pump was chosen for the detached house in Naantali due to the predictability of heating costs and the sufficiency of hot domestic water.
Mirka Aittola and Riku Saarela thought they would never build a house. But that’s just how they have been living with their 6- and 2.5-year-old sons in a log house they built themselves in a new small house area in Naantali since the end of May.
It is a unique Kontio log house designed by architect Jouni Berg, with a total living area of 174 square meters and the house also includes a 30 square meter loft.
The couple has changed their minds about housing once before.
When the large two-bedroom apartment in the center of Turku became small five years ago due to the addition of a family, the family did not want to buy a detached house and definitely wanted to stay in Turku. Be that as it may, they ended up purchasing a single-family house built in 2014 in Merimasku in the Naantali archipelago. When the younger son started wanting a room of his own, Mirka and Riku started looking for a new home closer to the center of Naantali.
– None of the ready-made detached houses really caught us, Riku recalls.
Little by little, the couple got excited about building a detached house, and it was also clear that they didn’t want to move away from Naantali.
Mirka and Riku fell in love with Kontio’s Glass House, but in a slightly modified version. In the end, Riku’s friend Ville Hänti, who works as Kontio Turku’s regional salesman, pointed out that the architect’s plan should be implemented as an individual object.
The construction of the house started with earthworks in the beginning of 2021. There used to be a large pit on the plot, possibly from the Tammisto Brick Factory that was located in the area between 1904 and 1944. The pit was dug one meter deeper and a total of 2,700 tons of ore was brought over. At its thickest, the quarry layer is three meters long.
When the building crew finished their work, Riku and his father were left to fend for themselves. Building is in Riku’s bloodline. Even his grandfather was a carpenter and a lumberjack. In addition to his own work, Riku’s father built two houses for his family and many for others as well. Riku has helped with the installation of the bituminous ceramic roof since he was a kid.
First, the interior surfaces were completed in the technical space located in the hall of the house, because the Jämä Star RST Inverter geothermal heat pump that heats the house and its domestic water had to be installed there. The device has a speed-controlled inverter compressor that automatically adjusts to meet the power needs of the house and domestic water. Thanks to it, optimal efficiency is achieved all year round.
The device’s annual efficiency SCOP is a whopping 5.4. The volume of the integrated stainless steel hot water storage tank is 180 liters.
Mirka and Riku ended up with geothermal heating largely based on the experiences of the previous house. Getting the exhaust air heat pump adjustments right was laborious and you couldn’t count on enough hot water.
– The worst thing was the unpredictability of the electricity bills. In the summer, the electricity bill could be 100 euros per month, but in the cold winter months it jumped to 400 euros.
Riku compared different forms of heating on Motiva’s website and the perception of the superiority of geothermal heat was strengthened. What excited me the most about the ground source heat pump was the uniformity of the consumption of electrical energy, regardless of the season.
Riku compared the bids sent by local operators with the master in charge of his project.
– The Jäspi solution offered by Kaarina’s Lämpö Nurmi Oy was already perfect during the bidding phase. Everything was already thought out. The person in charge also praised that a well-thought-out offer guarantees that there will be no surprises.
The price was also right.
The only change to the offer was the abandonment of a separate hot water heater, as it would not have fit in the compact technical space in addition to the Jäspi Buffer buffer heater required for underfloor heating.
– However, the seller assured us that we will be fine with the device’s internal 180-liter storage tank, as it is enough for the needs of a family of five.
After drilling a 180-meter deep energy well and installing the system, the geothermal heat pump was turned on in December 2021.
– The electricity consumption figures on Naantali Energia’s website are quite difficult to look at. After the geothermal heat pump was started and the blowers were blown, electricity consumption literally collapsed, Riku laughs.
An excellent purchase
When the family begins to have living experiences for half a year, the geothermal system has already had time to show its ingenuity. Warm water has been abundant. Of course, underfloor heating has not been needed in the summer season other than in damp rooms.
– I just checked on our electricity company’s website that our total consumption has been around 1000 kW per month. The lion’s share of it comes from the heating of Novitek’s hot tub, which is kept at full power, Riku says.
In winter, the reserve fireplace in the living room is also put into regular use. Mirka praises the peace of mind brought by the predictability of the monthly expenses of the geothermal heat pump. The couple’s electricity contract is still very affordable for a while.
– The geothermal heat pump is also incredibly quiet, Mirka adds.
The device is in the hallway behind the sliding doors and is not soundproofed in any way. Still, you can’t hear its running sound – unlike the exhaust air heat pump in the previous home.
Mirka and Riku are sure that they will live in this house for the rest of their lives. There is no need to build a new one, even though the construction project was not that difficult.
– We were together a lot, laughed and fought, Riku recalls.
– We finished the house and we are still together – many experiences richer!