January 19, 2026

Market Hall replaces air handling unit – saves 160,000 kWh/year

With a payback period of 3.7 years, the market hall’s new air handling unit is an investment that pays for itself quickly – a sustainable combination of energy efficiency and comfort.

Market Hall | Lahti, Finland

Lahti Market Hall has been a meeting place for visitors for more than a century. In 2025, the building underwent an extensive renovation to restore it to its original appearance. The market hall is centrally located in Lahti’s market square and offers genuine Finnish flavours and locally produced ingredients. As part of the renovation, an older air handling unit was replaced with a new, energy-efficient unit. This will result in annual energy savings of around 160,000 kWh, with a payback period of 3.7 years.

Investment calculation formed the basis for the investment

At the beginning of the project, Intervent’s sales representative prepared an investment calculation that clearly showed energy savings, operating costs and the payback period. The calculation showed good profitability and formed the basis for the investment decision. By replacing the existing air handling unit, the property owner can now reduce both energy use and operating costs, while the payback period for the investment is estimated at 3.7 years.

Envistar Flex with rotary heat exchanger

The market hall was previously ventilated with an older supply air unit without energy recovery and belt-driven fans that consumed a large amount of energy. The retail space is now served by a new supply and extract air unit with a rotary heat exchanger that recovers more than 80 % of the air’s heat.

Watch a video about the Easy Access concept

Easy Access facilitated site transport

The new unit was delivered in Easy Access configuration – a modular solution with dimensions adapted to be transported through standard doors. This meant that the installation could be carried out without having to make any modifications to the culturally and historically valuable building.

The designer had originally specified a different air handling unit, but there were limitations in the plant room and transportation routes were narrow.

Pasi Kivimäki, Supervisor at LVI-Kiviaho

“The designer had originally specified a different unit, but there were limitations in the plant room and transportation routes were narrow. We opted for Intervent because they could offer a customised solution,” says Pasi Kivimäki, Supervisor at LVI-Kiviaho.

Jussi Kaihlanen, sales representative at Intervent, conducted a site inspection and verified that both transportation and installation could be carried out without problems.

“The unit was transported by lift as far as possible, after which we carried it up the last few floors. The installation proceeded quickly and smoothly,” says Kivimäki.

Good indoor climate for decades to come

Lauri Kolli, property manager at the Kollin Foundation, which owns the market hall, notes:

“The renovation has been an important technical and financial investment, but also a cultural investment to preserve and develop Lahti’s city centre. Thanks to the improvements, the market hall will continue to serve both customers and operators for many decades to come,” concludes Kolli.