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If you’ve spent time wiping streaming windows and mopping up watery windowsills, you’ll know how troublesome condensation dampness can be. The problem is excess water vapour and it makes itself very easy to spot.

A common first-step to tackling the problem is trying to reduce moisture levels in the worst-affected rooms. Dehumidifiers are a popular choice, as are portable moisture-absorbing products. But the initial signs of condensation dampness – most noticeably streaming windows – are part of a wider problem. Tackling individual rooms is, unfortunately, treating the symptoms and not the cause.

What Causes Condensation Dampness?

Condensation dampness is caused by excess humidity. The average family of four produces around 10 litres of water per day simply by cooking, bathing, washing and drying clothes, and even breathing. All that moisture is absorbed into the air and travels to the coldest parts of the house where it condenses on cool surfaces like walls, windows and furniture.

Humidity and damp surfaces encourage mould spores to germinate. The tell-tale sign of black mould appearing on walls, often in cold corners and behind large pieces of furniture, is often what drives homeowners to seek out professional advice. Rightly so; black mould looks unsightly and simply reappears after surfaces are cleaned and repainted.

While mopping sills and wiping away mould patches are laborious, it’s what you can’t see that actually does the most harm. Mould spores are an allergen that aggravate asthma symptoms. Recent evidence suggests that living in a damp environment can actually cause asthma, and those spending over 16 hours a day at home are most at risk.

A damp, humid environment also provides the ideal breeding ground for the household dust mite. This little blighter, while microscopic and harmless enough, produces faeces that travel in the air and irritate the lungs of asthma sufferers.

Condensation Dampness Keeps Bad Company

If humid air stays trapped inside the home, then so do the other main culprits of indoor air pollution: CO2, nitrogen dioxide, formaldehyde, and Volatile Organic Compounds (VOCs), amongst others. These chemicals and gases are given off from burning fuel (using a gas stove, lighting fires or using a wood burner); from cleaning, DIY and beauty products; from cooking, smoking, and even from your gas central heating system.

A recent report published earlier this year by the Royal College of Physicians has revealed some alarming statistics about the impact of indoor air pollution on our health. Indoor air can be up to 50 times more polluted than outdoor air, containing up to 900 potentially dangerous chemicals. This can increase our chances of developing serious illness including lung cancer and heart disease.

Tackle the Cause, Not the Symptoms

Condensation dampness becomes a problem if the home isn’t adequately ventilated – not enough fresh air is coming in to replace the stale, humid air. The problem is worse in colder weather as the fabric of the home gets cooler and moisture-laden air is drawn to the coldest surfaces. It’s most evident in homes that aren’t consistently heated or that suffer from cold spots, but is also a consequence of insulating walls and lofts to improve energy-efficiency as the humidity is effectively sealed inside the home.

Extract fans can help remove moisture in the immediate area, but as they work intermittently and are activated when humidity levels are at their highest, they are not powerful enough to ventilate the whole house and extract the excess water vapour that causes damp.

In order to reduce moisture levels and clean the indoor air, an average of four air changes per hour is required. This is a job for whole-house ventilation, which ensures that a property is ventilated throughout, not just in the wet rooms.

The most effective way of nipping condensation dampness in the bud, and improving your indoor air quality, is to install a Positive Input Ventilation system, or PIV, as it’s known in the trade.

How a PIV System works

How a PIV system works – image courtesy of nuaire.co.uk  

This technology was invented by a British company called Nuaire over 40 years ago. PIV involves drawing fresh air from outside into a fan located in the loft area where it is filtered, tempered, and gently pushed into the home via a ceiling diffuser. This process works continuously; forcing out stale, moisture-laden air and significantly reducing both the humidity levels and the airborne allergens. It creates a healthy indoor environment in which condensation dampness cannot exist.

Fitting a PIV System

The latest Nuaire PIV is the Drimaster PIV range. Drimaster-Eco can be installed in under one hour by one tradesman, with no external core cutting, no duct runs and minimal disruption. With the exception of the wiring, where we recommend getting a qualified person to help, this is actually a great DIY project. Have a look at the video:

How to install a PIV system

Watch the video on how to fit a PIV system here.

The Drimaster-Eco PIV system is the modern, circular ceiling diffuser which houses all the system controls. This allows full operation of the unit, including commissioning and adjusting the settings, from the hallway without having to enter the loft. Maintenance is minimal as the Drimaster-Eco filters are changed every five years and come with a 7 year warranty.

The Drimaster-Eco range includes several models to suit specific needs. The Drimaster-Eco-Link and Drimaster-Eco-Heat versions both have enhanced hall-control with remote control and sensor capabilities. You can boost the fan speed, adjust the system when more moisture is being produced and when CO2 levels rise above a set point.

The Drimaster-Eco-Heat has an integral heater which sits between the flexible duct and the diffuser. This means that more of the heat created is used to temper the air rather than losing 3 to 4 degrees of heat through the duct as per standard PIV designs, making it up to 20% more energy efficient than traditional models.

Drimaster PIV system

Drimaster-Eco PIV from Nuaire – Buy from Amazon here or you can also Buy from Ebay here

The effectiveness of PIV at preventing condensation and improving indoor air quality has been proven by countless research studies over the past 40 years, and this popular ventilation principle is supported by a BBA certificate and recognised as an alternative method within building regulations. PIV is also one of three solutions to significantly reduce harmful Radon gas levels for homes in affected areas.


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