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Prerequisites for good indoor air – 6 key factors


​The prerequisites for a good indoor climate are created at the building's design phase. This means, for example, the documentation of the customer's objectives, specification of the design objectives, and sufficient investment in ensuring that the finished building functions in accordance with the plans and the objectives set in them. Read the other five key factors that you should take into account.


The prerequisites for a good indoor climate are created at the building's design phase. This means, for example, the documentation of the customer's objectives, specification of the design objectives, and sufficient investment in ensuring that the finished building functions in accordance with the plans and the objectives set out in them.

A key objective is to get the building's structures, shell and building technology systems to work in harmony, taking into consideration the different usage and load situations of the property. This requires good information exchange, cooperation and coordination between the different design and implementation parties, as well as a competent maintenance staff inducted in their duties well in advance.

The indoor air quality can also be guaranteed in the design phase by choosing building materials tested to have low emissions and ensuring that moisture management is taken into consideration during construction.


Cooperation and a methodical approach play key roles during the construction phase as well. During construction, structural, equipment and installation method inspections are carried out in the agreed manner together with the developer and the contractor. Quality assurance at the construction site is particularly important in order to avoid hidden flaws.

Important issues at the construction site include the weather protection of structures, sealing, the implementation of water removal during construction, the moisture management plan, storage and logistics  and the prerequisites for functional tests. It must also be ensured that all actors on the construction site have sufficient information and skills to carry out their own parts in the manner required by the plans.

Scheduling is also a key factor – how can you ensure that the structures have time to dry before coating and that the functional tests on the building technology are carried out thoroughly and at the right time.

During the construction phase, no compromises must be made due to haste regarding the sufficient drying times of the structures specified in the design phase. Excess moisture during the coating phase may lead to the chemical decomposition of the material, causing indoor air problems in the form of health effects or odours.


Ventilation that is correctly designed and carefully implemented, modern, silent, draught-free and adjustable according to need provides fresh indoor air in any weather and at any time of the day. Indeed, it has been observed in analyses of buildings with indoor climate problems that an incorrectly designed or implemented ventilation system may cause and aggravate problems related to indoor air quality.

The management of pressure differentials is critical for the functionality of ventilation. A lot of complaints have been made due to pressure differentials caused by separate air extraction, which has also caused indoor air problems and difficulties in using a fireplace.


An energy-efficient building is warm and draught-free. The floors, walls, corners and windows are comfortably warm. There is no draught in the corners and joints, nor are there air leaks or cold bridges causing moisture problems.

In an energy-efficient building, the intake air is filtered clean and warmed until it does not cause draughts. In a well-designed and well implemented energy-efficient building, even challenging changes, such as drastic changes in outdoor air temperature, the effect of wind or human activity, are situations where the indoor climate remains evenly comfortable.

However, the air volumes or ventilation should not be needlessly reduced in the name of energy efficiency. Particularly in new buildings, materials emissions are always high, even if low-emission products have been selected. For this reason, the ventilation of a new residential building should be kept on the high-power setting for at least six months. This procedure reduces exposure and later complaints related to indoor air quality.


Functional structural solutions taken carefully into implementation from the designer's desk prevent moisture and mould damage. In order to eliminate errors and ensure functionality, third-party evaluations of the thermal and moisture-technical functionality should be used.

However, microbes are a part of our natural living environment, and their presence in the structures is inevitable. Solutions that function safely in the thermal and moisture-technical sense can be used to minimise the presence of harmful microbe growth. Quality control and monitoring the functionality of the finished building is important. Any problems detected must be addressed immediately and corrected properly.

The construction materials should be selected so that they cause the least possible amount of emissions and impurities.


The how and what of interior decoration are also not entirely trivial. Furniture and textiles often release more emissions to the indoor air than people think. The correct choices here, as well, are very significant for the end result.

When planning and choosing furniture, objects and equipment, cleanability should be given attention. Consciously made, sensible decisions on construction and interior decoration materials form the foundation, but things such as dust-collecting surfaces should be avoided as well.

On the other hand, various pieces of office equipment can spread impurities very effectively. Good cleaning is also a must for a dust-free indoor climate. Service and maintenance throughout the entire life cycle of the building will ensure that the good indoor climate achieved can be maintained.


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