The silent intruder

Nicola Rivers, Indoor Climate Specialist at Zehnder Group UK, discusses the importance of understanding the impact of condensation in commercial buildings.

With colder nights drawing in and the heating being ramped up, we start to spend more time indoors and enter hibernation mode, be it at work or home.

We seek out cosy spots, put the kettle on hundreds of times and close doors and windows but in our bid to stay warm we overlook the harm our human behaviours have on the buildings in which we reside.

I’m talking of course about condensation, the often-overlooked adversary in buildings, commercial and residential, that silently creeps into spaces, leaving behind a trail of consequences that can significantly impact the structural integrity, occupant health, and overall efficiency of a facility.

Despite its seemingly innocuous nature, condensation is a pervasive issue that demands attention and proactive measures within the realm of commercial building management.

No building is immune. Warehouses, schools, restaurants, offices, hotels and even hospitals can fall victim. Older buildings that are not insulated are most at risk but newer buildings with inadequate airflow can also be vulnerable as we seek to better insulate for net zero gains.

Condensation occurs when warm, moisture-laden air comes into contact with a cold surface, causing the water vapor to transform into liquid water. It is especially prevalent in commercial buildings because of temperature differentials between indoor and outdoor environments, as well as variations within the building itself. Without effective ventilation within the building, the airflow is restricted and humidity build-up exasperates the problem.

Condensation on its own shouldn’t be cause for alarm despite being an irritant and leading to financial implications. However, where condensation forms on roofs and walls in colder conditions, the drips can lead to damage of internal finishes, machinery or materials as well as add to health and safety dangers within the workplace.

What is more alarming is that, if left alone, condensation can lead to damp and turn into black mould which is toxic to occupants.

A recent survey by the British Property Federation found that 70% of commercial buildings in the UK had evidence of mould growth while similar studies by the Health and Safety Executive found that 40% of workers in the UK had been exposed to mould in their workplace. In its 2021 study, researchers found that exposure to mould in commercial buildings was associated with an increased risk of hypersensitivity pneumonitis, a serious lung disease.

Mould can cause a number of health problems for anyone who spends time in the building, including employees, customers, and visitors. This can range from a blocked nose and sore throat to itchy skin and in winter these symptoms are often mistaken for those of the common cold.

In extreme cases mould can cause severe health issues and even death. For example, a 2022 study by the University of Birmingham found that exposure to mould in commercial buildings was associated with an increased risk of asthma attacks, especially in children.

Building damage and poor indoor air quality

One of the primary concerns associated with condensation in commercial buildings is its potential to compromise structural integrity. Moisture accumulation can lead to the decay of building materials, promoting the growth of mould and mildew. Over time, this can weaken the structural components, resulting in expensive repairs and jeopardising the safety of the building.

Furthermore, condensation on metal surfaces can initiate corrosion, accelerating the deterioration of essential structural elements.

This is particularly problematic in buildings with extensive metal infrastructure, such as warehouses and manufacturing facilities. Regular inspections and maintenance are crucial to identifying and addressing these issues before they escalate.

Condensation not only affects the building’s physical structure but also has a direct impact on indoor air quality. We know that the average family produces 24 pints of water vapour a day through routine activity – just think how much more that becomes in a working environment. The times the kettle is boiled in an office, cooking from commercial kitchens and canteens, even showers at the gym.

The damp environments created by condensation provide an ideal breeding ground for mould and mildew, releasing spores into the

Nicola Rivers
Nicola Rivers of Zehnder

air. Inhalation of these airborne contaminants can lead to respiratory issues, allergies, and other health concerns among building occupants and without effective means to ventilate the building and reduce the humidity in the air, the problem

grows or keeps returning.

It isn’t just health and structural concerns that we need to consider, however. Condensation-induced moisture can also compromise the effectiveness of insulation materials, reducing their thermal resistance and contributing to uncomfortable indoor temperatures.

This constant battle between warm indoor air and cold exterior surfaces necessitates increased heating or cooling efforts to maintain a comfortable temperature within the building. It is this heightened demand for energy that not only strains HVAC systems but also translates into higher operational costs for the commercial property.

Mitigating the impact

Addressing condensation in commercial buildings requires a multi-faceted approach.

Investing in proper insulation and effective ventilation systems can help regulate indoor humidity levels, minimising the conditions conducive to condensation. Routine inspections and maintenance are essential to identify and rectify potential issues before they escalate, safeguarding the structural integrity of the building.

In some cases, a building will have a ventilation system that should work for the building it serves, yet condensation problems still arise.

This could mean that the system was installed incorrectly and needs to be reviewed or checked. No commercial ventilation system, installed and performing correctly by a competent M&E contractor, should have humidity build up to that degree.

Alternatively, if a building is a multi-purpose space or has seen alterations in its layout, be it through expansion or refurbishment, this complexity is further compounded. What may once have constituted an effective method of air circulation during the initial construction may no longer prove suitable. For example, when an internal structure of an office is modified owing to a change of use or increase in personnel.

Adjusting the ventilation system to address these modifications isn’t always a feasible option and, in these cases, systems will need renewed consultation to assess the requirement and maintenance going forward.

A ventilation system must also be serviced properly to ensure it functions as intended. Regular maintenance of these systems is crucial - such as changing filters annually and ensuring extract fans are in operation.

‘Though often overshadowed by more overt building issues, condensation poses a substantial threat to the structural integrity, occupant health, and operational efficiency of commercial buildings.

Acknowledging its presence and implementing proactive measures are paramount to mitigating its impact.

Where sustainability and energy efficiency are at the forefront of building management concerns, addressing condensation is not just a matter of maintenance.

It’s a strategic investment in the longevity and performance of commercial structures and people’s health.

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