Occupants and Interiors  

Why do we have systems for ventilation, cooling and heating?


Essentially, human physiology dictates the desired indoor climate, in which our ‘creature comforts’ and health criteria are focal. In this Guide, we review a number of key aspects of the indoor climate, and offer our advice on smart solutions that make it easier to fulfil system requirements specifications for a given system - before, during and after installation.

What factors affect the indoor climate?

Thermal climate

This is the one single factor that typically has most impact on the perceived indoor climate. This is influenced in turn by heat output by means of radiation to surrounding surfaces, convection to ambient air and evaporation of liquids. Depending on the activity-level of the occupants, and the type of clothing worn, a given room temperature will be perceived differently. An awareness of these factors when planning the indoor climate system for a space is important in identifying an effective solution, but in the last analysis, it is also crucial to be able to adjust the chosen solution to subsequent tenant-level changes. This calls for highly adaptable products with the capacity to cater for increased demand for air flow and cooling for example.

Acoustic environment

Sound can be generated in many ways in a climate system and cause annoyance at the time, and even pose a health hazard in the long term. With the right insights and products, this problem can also be resolved. Any noise can be minimised at source, and dampened if it occurs. 


The natural light that enters an interior through windows is likely to provide much of the well-being factor, but usually needs to be supplemented by artificial lighting in some form to permit work to be done at all hours. Extensive fenestration has grown in popularity in the last decades, but a key factor in that context, certainly the further north you are, is that solar radiation can deliver a valuable volume of energy to an interior, especially in south-facing aspects over the spring and autumn. This makes it essential to use simulation software for determining the added heat loads, and addressing measures such as sun-screening.

Relative humidity

If the relative humidity is too high or too low, it can adversely affect comfort and health. An excessively dry indoor climate, for example, can cause sensitisation of the mucous membranes and raise sickness-absence rates among occupants. Against that, an overly humid indoor climate can cause harmful proliferation of moulds etc. A climate system that controls air humidity with sensors at room level and which via the air handling unit effectively controls supply air humidity by means of a sorption rotor, for example, promotes human health, and does so energy efficiently. 

Air quality

The very essence of a ventilation system is to remove air pollutants that inevitably arise in an occupied space. Measuring the carbon dioxide content provides a good indication of the occupancy rate. An alternative, or supplementary, metric is the level of volatile organic compounds (VOCs), which also indicates other types of pollutants originating from both people and objects such as furniture and construction materials. Based on these data, the ventilation system can then adapt the air flow. With a well-developed master system for demand-controlled ventilation, there is high potential for ensuring healthy air quality with minimal energy consumption.

Air velocity

People perceive the velocity of air flow differently depending on its turbulence and temperature. To facilitate spatial planning, a template threshold value has been defined for the maximum permissible air velocity in the occupied zone of 0.15 m/s.One useful physics principle to apply in this context is known as the Coanda effect, whereby air supplied in the right way to a surface, e.g. a suspended ceiling, has an affinity for that surface. This means that the air flow “hugs” the ceiling instead of causing draughts at the centre of the room.With intelligently designed products, it is possible to optimise the volume of air supplied to an interior. Air diffusers with discs and comfort modules with air flow deflectors can adjust the air distribution to cater for the room layout, and ensure that the supply air is mixed successively with ambient air to attain a comfortable temperature, and is stopped so as not to disrupt the climate in the occupied zone.

People and spaces

The past decades have seen major changes in where and how most of us spend our time, but we humans basically still function in the same way as we did thousands of years ago. By concentrating on people when designing our indoor climate systems we can maintain a high level of comfort, which has a positive effect on both our performance and long-term health.

The room in the indoor climate system

When you know the requirements of the people in the room different approaches can be employed to satisfy these. Here you have to assume the prerequisites for each project – how the building’s level of comfort is evaluated in relation to investments and energy aspects? It’s a question of finding a balance between the set requirements. Technical solutions can be found on different levels, and the secret is to get the maximum dividend from each investment regardless of budget.

Parts of the building process