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Planning an energy renovation? Find savings with right solutions!

Renovation examples of apartment and town houses from Lahti are in free use for everyone. Investment calculations are also included. Explore and get inspired!

Small and agile actions

Budgeting for an energy renovation can seem like a heavier decision than it actually is. Some of the measures that improve energy efficiency are easy and inexpensive to implement. In the joint project of the city of Lahti and rental housing company Lahden Talot, it was noticed that the renovation costs could pay for themselves in just a few years, when heat and electricity consumption could be reduced.

You can familiarize yourself with these small but effective measures below.

  • Air-wa­ter heat pump

    Thermal energy stored in the ground and air from the sun can be utilized using heat pumps. Waste heat recovered from exhaust air and waste water can also be used to heat living spaces and domestic water.

  • Wa­ter sa­ving so­lu­tions

    New water fixtures, such as faucets and toilet seats, or maintenance of old ones in the kitchen and bathroom can significantly reduce water consumption in a residential building.

  • In­tel­li­gent hea­ting cont­rol

    Real-time monitoring of living conditions with the heating control system helps to balance the heat indoors to the optimum level. You shouldn’t overheat an empty home.

  • More than 80 percent of the energy needs of living comes from heating apartments and domestic water.

    An air-to-water heat pump was installed in a townhouse complex built in 1991 alongside the new oil heating system. The investment paid for itself in just over a year, when the saved energy costs are taken into account.

    The energy efficiency class of the property, which includes four townhouses and 18 apartments, improved from class F to class C.

    More on the topic

    Familiarize yourself with the renovation site report.

  • Households use hot water throughout the day in the kitchen, shower and washing machines. Heating domestic water alone is about 17% of the energy needs of living. The energy renovation of an apartment building built in 1997 focused on water saving solutions.

    In the 26 apartments of the apartment building, the nozzles of the shower handles and faucets were renewed and the toilet seats were maintained. Analyzing the domestic water system and replacing water fixtures will pay for themselves in water and heating energy bills in about five years.

    More detailed information

    Check out the renovation site report

  • Heating is one of the biggest costs of housing associations. It takes about 65% of the energy needs of living.

    A smarter heating control system was purchased for an apartment building in the center of Lahti, built in 1951. Real-time Leanheat heating control works remotely using the weather forecast. Ambient sensors that monitor temperature and air humidity do part of the work. The payback period based on energy savings is about three years.

    More on the subject

    Familiarize yourself with the renovation site report.

  • Since heating takes as much as 65% of the energy needs of living, new solutions must be constantly sought alongside with the finished energy saving actions.

    In a 94-apartment student apartment building in Lahti, a solution to reduce carbon dioxide emissions was tendered as an innovative purchase. Thus a mobile user interface was developed through which the resident can monitor the temperature and humidity measurements of the apartment and give feedback on the living conditions. The calculated payback period for a smart heating control system that takes feedback into account is about seven years.

    More detailed information

    Check out the renovation site report. 

  • The heating control systems were improved in three Lahti Talot owned properties, each in slightly different way.

    One heating control system was installed in the townhouse site built in 1992, which improved the living conditions. The temperature can now be adjusted for each room and changes can be scheduled for regular absences. The calculated payback period is about eight years.

    More on the topic

    Familiarize yourself with the renovation site report.

Solutions that bring savings in the long term

In the joint project of the city of Lahti and Lahti Talot, also larger renovation measures that provide significant benefits in the longer term were studied.

  • Exhaust fan

    The energy efficiency of mechanical exhaust ventilation improves when old exhaust fans are replaced with new energy-efficient devices. The controllability of the exhaust fans should also be improved.

  • Solar panels

    The installation of solar panels must be planned considering many different factors: for example shading, installation technology, roof materials, orientations and the property’s electricity demand essentially affect the optimal installation on the building roof.

  • Wastewater heat recovery

    When the waste water flows through the heat recovery system, the contained heat is transferred back to use in the property. In this way, energy can be recovered from the heated service water, which would otherwise end up in the sewage system along with waste water.

  • In an apartment building in Nastola, Lahti, built in 1987, the biggest costs, i.e. heating costs, were reduced with a new ventilation system. A new exhaust fan and improved steering were key measures.

    In an apartment building with 17 residential apartments, the former energy efficiency class E was improved to energy efficiency class D through renovation. The payback period for the measure is about 10 years.

    More on the subject

    Check out the renovation site report

  • The payback times for installing solar panels vary significantly by property and house type. In addition to the investment cost, the payback period is affected by the utilization of solar electricity directly at the destination, thus avoiding transfer fees and electricity tax. Calculations of the installation and investment costs of solar panels were made at the sites of the rental housing company, Lahden Talot. Payback periods varied between 10 and 20 years.

    The production of solar electricity and the electricity demand of the building must be optimized precisely in order to get the best possible benefit from the solar panels. The compensation received from solar electricity fed into the grid is currently relatively small, so self-produced solar electricity is more beneficial to be used on-site in the building.

    The output of a solar panel essentially depends on its orientation and tilt angle. The installation method of the solar panel must be chosen on a case-by-case basis according to the installation surface. For example, the type of water roof has a significant impact on the installation method.

  • Heating domestic water takes about 17% of the energy needs of living. Most of this amount of energy ends up in the sewage system along with the wastewater. Wastewater heat recovery can be realized with a heat exchanger connected to the building’s sewer line.

    A wastewater heat recovery system was introduced in the 190-apartment service building. The system was installed as an additional heat source for the geothermal system, and the geothermal heat pumps were renewed at the same time.

    The property was selected for the experiment, because water consumption is high in a large service building. Warm water is used in abundance, so heat is also readily available. The calculated payback period for the measures taken in the new property is about 17 years.

    More detailed information

    Familiarize yourself with the renovation site report. 

  • A new oil heating system should be serviced and maintained. Although it is generally encouraged to give up fossil fuels, it is worth renovating the newly existing and functioning system as necessary.

    Renewing the oil burner improves reliability and efficiency. As a rule of thumb, the replacement time for the burner approaches when its service life is over ten years.

    The service life of an oil boiler is about 25 years. You should consider renewing the boiler when the age of 20 years is exceeded. The profitability is clearly improved, but on the other hand, the investment is greater than simply renewing the oil burner.

    In the Takojantie town house in Lahti, the oil burner and boiler were renewed. The calculated payback period is about 13 years.

    More on the topic

    Check out the renovation site report.

Seven renovation sites and the implemented measures

You can find listed below the reports of all renovation sites

  • 7

    renovation sites

  • 414

    residential apartments

  • 41 500

    euros of savings per year

  • 492 000

    kWh lower energy consumption per year

  • 107

    tons less emissions per year

  • 25

    saving corresponding the electricity consumption of single-family houses (electric heating, 4 people, 120 m2)

Still hungry for information?

Below, we have compiled additional information links to reliable sources for the benefit of those considering energy renovation.

  • The low-carbon solutions for renovation construction project is part of the wider Towards carbon-neutral municipalities and provinces project (CANEMURE). The sub-project in Lahti is looking for solutions to reduce the energy consumption and climate emissions of the existing housing stock as cost-effectively as possible. Renovations and energy measures of the Lahden Talot are on the main focus. Lahden Talot Oy is a company owned by the city of Lahti that builds and owns rental apartments in Lahti.

    In the project, seven sites have been renovated and monitored, where various energy renovation measures have been carried out. The cost effectiveness and emission savings of the measures have been calculated and the results are actively communicated in Päijät-Häme Region, Finland and internationally.

    The measures support both the city of Lahti’s goal of carbon neutrality by 2025 and the environmental goals of Lahden Talot.

    The national CANEMURE project, which started in 2018, will end in 2024. The aim of the project is to promote smart low-carbon transport, increase the production of decentralised renewable energy and improve the energy efficiency of buildings. A large part of the project’s funding comes from the EU’s Life program. The Finnish Environment Institute SYKE is responsible for coordinating the national project.


    The production of this project page has received funding from the LIFE program of the European Union. The content represents only the views of the CANEMURE project and the EASME/EU Commission is not responsible for the possible use of the information contained on the site.