In Laajasalo, a complete ventilation renovation was carried out for a family of four in an older detached house. The gravity ventilation was replaced with energy-saving ventilation.

The ventilation system in the old house started working after the ventilation renovation.

Leena Tuominen and Peter Spodniak, along with their two daughters, moved to a beautiful old detached house in Laajasalo, Helsinki. The building needed a bit of updating after its previous residents, so a cosmetic renovation has been underway on all three floors. However, ventilation hadn't been carefully considered in the old building, so the gravity ventilation required some upgrades. Measurements revealed deficiencies in the old ventilation system. Read the story in the article and watch the installation video of Fresh's ventilation installer's masterful work.

How did the ventilation renovation start?

The renovation began with measurements and planning by Freshil's ventilation professionals. The building was properly measured for the pressure difference across the outer shell, carbon dioxide levels and their removal from living spaces, gas levels which were slightly elevated, VOC levels which provide more detail on volatile gases floating in the breathable air, air humidity which in turn provides more detail on the moisture balance maintained by the ventilation system compared to outdoor air, and air pressure.

A closer inspection of the house quickly revealed that there was too much negative pressure in the house, even though the building had gravity ventilation. Its operation is based on differences in indoor and outdoor weather conditions and the shaky structures, as there were hardly any wall vents in the building. The situation was further exacerbated by the fact that the building had plasterboards on the exterior walls and thick, old-fashioned plaster, which hardly allows air to exchange through the wall structure.

What kind of ventilation problems did the old house have?

Based on quick on-site investigations and measurements, it was determined that the ventilation was not at a sufficient level. Carbon dioxide levels rose rapidly when the family was home for a few hours, and did not start to decrease even when the family moved to another room. In addition, there were high levels of carbon dioxide in the bedrooms during the night, which is why mornings may not be the most energetic.

In addition to a bathroom and sauna, the basement houses a boiler room and a larger workspace with a fireplace. It was determined with a smoke pencil that the fireplace chimney in the basement was operating in reverse of its intended function. The operation of gravity ventilation in old houses is based on directing the fireplace chimney as high as possible, so that when the warm air begins to rise upwards and the air pressure is higher below than above, the air should begin to rise up and out through the chimney, thereby expelling air from the house. However, this was not the case in Laajasalo. Instead, the house had such a strong negative pressure that air was entering the family's breathing air through the chimney. This is, of course, undesirable, as a chimney is known to be full of fine particles, and fine particles from fireplaces are in no way healthy; on the contrary. They have been identified as the biggest cancer risk, along with gas, in low-rise residential areas, and attention has increasingly been paid to wood burning in low-rise houses for health reasons.

What kind of ventilation renovation was done for the gravity ventilation?

In a three-story detached house, it's important to consider that pressure differences can vary greatly between all floors. Generally, the top floor has positive pressure and the bottom floor has negative pressure. Pressures can be equalized, and the building can be made healthier and safer to live in if an appropriate ventilation system is designed for the building.

A modern Fresh ventilation renovation was carried out in Laajasalo, and Fresh's heat-recovering room-specific ventilation units were installed into one functional ventilation system. Each floor received 2-4 room-specific ventilation units, and replacement air vents were installed into the windows in the boiler room and the corridor on the middle floor, i.e., window trickle vents.

The ventilation renovation would have cost a total of €28,000 with a traditional heat recovery ventilation unit, but since the work was done using Freshin’s unique ventilation system, the turnkey installation was completed at one-third of that price. In addition, after the Freshini installation, the customer received a breakdown of the home improvement work, which allows them to claim a 50 % tax refund from the tax authorities at the end of the year as a home improvement deduction for Freshini’s portion of the work. The household tax deduction is a full deduction and is not calculated ”on top of income” like many other tax deductions or surcharges.

The installation lasted 4 long days, even though the basement foundations were a strong, locally cast concrete slab, which was densely reinforced with finger-thick steel rebar. The installers had cleaned

What did the residents think of the ventilation renovation?

Before the renovation, Peter's concern was how to make his study warmer, as the floors were very cold, which is typical in old houses. The very next day after the renovation, Peter was amazed at how well the floors had warmed up and how effectively the ventilation system circulated air from near the ceiling, heating the entire house.

In addition, the negative pressure was completely rectified, and the post-measurement showed only 0-1 Pa of negative pressure between the building's interior and the outside air, which is a very good performance for ventilation systems, and fortunately, Freshin ventilation systems are capable of this. Whenever an old house is close to a 0 Pa pressure difference, one can be sure that everything is working excellently. Fireplaces no longer sucked fine particles from the chimney into the indoor air, so we can expect a healthier life for the residents.

About three months after the renovation, Leena commented that ”We have been satisfied with the devices and after installation, as well as how the payment matters and other business were handled. Thank you!”