The Problem

One of the best-known indoor air quality issues, humidity causes a range of problems if not kept in check. Humidity refers to the amount of moisture present in the air and is something that needs to be balanced to create a healthy living environment. It is well known that a high humidity content has negative effects but at the same time, a very low humidity level can also be problematic, causing respiratory issues and dry skin along with other health issues.

However, the most common issue in the UK is with high humidity levels. Increased moisture suspended in the air not only creates an uncomfortable damp feel, it also makes the air heavier, slowing the speed of air circulation. This means that stale air is slower to disperse in indoor areas. To add to this issue, the moisture in the air can also hold a higher level of airborne pollutants trapped in the water molecules. This can lead to increased risk of respiratory problems along with aggravating existing issues such as asthma and allergies.

The higher moisture content can also become a breeding ground for viruses and bacteria as well as the ideal conditions for mould to thrive when the moisture condenses onto surfaces causing damp patches. Damp surfaces create the perfect environment for mould to develop. Not only do moulds cause damage to structural surfaces, but they also release spores into the air to multiply which can become a very hazardous airborne pollutant.

The Solution

With all the above problems relating to humidity, making sure you have adequate ventilation to help disperse the moisture from your indoor space becomes a necessary solution.

But it is not as easy as simply opening a window or two! Of course, in the warmer seasons there is usually a lower ambient humidity level present in the air and open windows can help to move fresh air into a building while displacing the stale air out. But if you live in an urban setting this can raise the level of pollutants, including noise pollution, entering the building. This is not a “whole year round” solution either. Aside from the obvious downside to losing heat through an open window in colder months, this allows cold air into the building. Colder air will also start to condense any internal humidity present faster when it comes into contact with it. Again, this makes the air heavier and harder to remove as well as speeding up the process of condensation forming within the building on surfaces before the humidity can be removed.

The best solution for reducing humidity is to install mechanical ventilation and maintain a suitable constant temperature. Both variables together create a healthy indoor environment. Ideally, Humidity should be controlled to a level less than a maximum of 70% and the indoor temperature ideally warm enough to minimise moisture condensing but no higher than 20°c - temperatures higher than this can create the perfect breeding ground for mould and other bacteria and viruses.

It is important to understand that it is impossible to eliminate all moulds and spores, but by creating an environment with dry surfaces that is as inhospitable for moulds to flourish as possible while keeping brisk air movement and air changes to reduce humidity and remove spores, the risk of damp and mould can be reduced exponentially. 

The Method

There are several ventilation options that can help either reduce existing humidity issues in structures, or that can be included in a new building design to protect against humidity and damp issues from forming in the first place. Many of these options will also help to protect against other forms of air quality issues, all of which help to promote a cleaner and healthier indoor air quality.

For new buildings MVHR (Mechanical Ventilation with Heat Recovery) units, that can be incorporated into the architectural designs prior to breaking ground, are at present the forerunners in terms of the mechanical ventilation of choice for the best protection. These units not only extract from multiple rooms giving a balanced comprehensive extraction across the structure, but they also introduce filtered clean, fresh air back into the structure that is warmed by harvesting the heat from the exiting stale air through heat exchangers to minimise heat loss and wasted energy. The units continuously cycle the air at a steady trickle rate, boosting automatically to a higher purge setting when the humidity rises above a set trigger level. As the incoming air is filtered, these units often have different grades of filtering options available, making them tailorable to different environmental factors such as hypo-allergenic filtering, pollen filtering and pollutant filtering amongst other grades of particle size filtering options.

For existing structures, MVHR units can sometimes be harder to retrofit due to the nature of their design. In these cases, MEV (Mechanical Extract Ventilation) units can be an easier, less intrusive option. MEV units are essentially half of an MVHR system, focusing on the extraction only rather than the reintroduction of air to a structure. But even these can sometimes be a problematic install in an existing structure due to the ducting needed. There are single room options here which can provide protection - single room HR (heat recovery) options can help to extract humidity and stale air while reintroducing warmed fresh air in the same process as MVHR units but on a smaller, single room scale and dMEV (decentralised Mechanical Extract Ventilation) units similarly work as a single room MEV system.

You can pair MEV and dMEV systems with a PIV (Positive Input Ventilation) unit which introduces fresh, filtered clean air centrally back into the premises, many of which also incorporate a heating element for colder periods and summer bypass options for hotter weather. These allow for the same level of filtered protection for the incoming air when paired with extraction only systems.

The Conclusion

Providing clean and healthy indoor air quality is essential for living and working environments, and with the ever-increasing need to meet environmental decarbonisation targets in structural developments, the need for mechanical ventilation systems to help support fresh, clean air supplies into increasingly sealed buildings for heat energy retention is becoming more and more important. Whether it is an existing building or a new build project, there is a system that will remove stale, humid air from your indoor environments and systems to help replenish with fresh, clean, and filtered air if needed. These will help you control your indoor air quality so that you can take a deep breath and relax in the knowledge that your environment is as healthy as your avocado on toast and your Peloton exercise bike.