Builders often reccomend passyfier vents, these work on the principle of air movement and pressure changes - eg when you open and close a door, but as you do not open and close doors all night when condensation is at it's worst (not if you want some sleep that is) their efficiency is limited. They will help to reduce but seldom cure condensation problems. Builders tend to reccommend them as they are easy to fit and you do not have to carry out any complex calculations for them. Passyfier vents have no moving parts, making them incredibly silent and energy-efficient. Unlike electric or desiccant dehumidifiers, they don't require any electricity to function, relying instead on natural pressure differences. The diffusion process is slow compared with mechanical ventilation and would not cope with the copious amount of water vapour produced in a short time scale without the combined use of mechanical ventilation in kitchens and bathrooms.

Increase ventilation where practical, IE when cooking close the kitchen door and open the window, when showering or bathing do the same. This reduces the influx of cold air from the outside, preventing excessive humidity and minimizing the chances of draughts. Until recently very little research had been done to prove the effectiveness of PIV and yet it widely specified. The BRE recently set up a parallel study to investigate the performance of PIV systems and carried out trials in their Watford test house and field studies in 16 Welsh properties. The study concluded with the following key findings:Passive ventilation makes use of natural forces like the buoyancy of hot air and wind to encourage airflow through your property. The result is that moist stale air is extracted and replaced with fresh clean air.

The opening where the Passyfier vent will be installed must be cleaned and prepared beforehand. Remove any loose debris, paint, or dirt and ensure that the surface is smooth and level. Input ventilation was found to be effective in reducing relative humidity levels by around 10%RH in the test house, even when internal doors were closed. Vapour pressures reduced overall by 0.2kPa. The unit was shown to be more effective upstairs than downstairs. and humidity at 100%, while the inside temperature is at a comfortable 20°C. Keeping the inside relative humidityThe Perma-vent passive air vent is environmentally friendly and requires no power, saving you money on your energy bills. It also has no moving parts and doesn’t require any maintenance. Passive Ventilation Products from Permagard escapes by diffusion through Passyfier Vents, which have been tested by ADAS for airflow rate versus applied Passyfier 100 Core Vent: With a water vapor transmission capacity of up to 1 liter per 24 hours, this vent requires a 132mm diameter core and is suitable for rooms with a floor area not exceeding 7m². Use the compatible wind blast cowl with every vent in exposed or coastal locations. Use in conjunction with mechanical extraction in kitchens and bathrooms.

Ensure that there is a good seal to the loft hatch. Many hatches are very poorly sealed and allow moist air to migrate into the roof space. occupied building than on the outside . This pressure is completely independent of that in the air. For example, a Energy-Efficient: Passyfier vents are incredibly energy-efficient, requiring no electricity to function. They rely on natural pressure differences instead, making them cost-effective and environmentally friendly.

Passyfier 140 Core Vent: With a water vapor transmission capacity of up to 1.4 liters per 24 hours, this vent requires a 162mm diameter core and is suitable for rooms with a floor area not exceeding 10m². Once you have created the appropriate opening for your vent, you can then insert the Passyfier Vent into the opening and secure it in place using the provided fixings. Be sure to follow the manufacturer's instructions carefully to ensure a proper installation.

The unit is designed to be very unobtrusive, with a 6" (152mm) internal white plastic grill. Externally all that can be seen is a 6" white plastic external grille. In the field monitored houses input ventilation was not consistently effective in reducing relative humidity. When internal humidity levels over those outside was examined, PIV was found to be effective in the most humid houses but did little in the dryer houses. Even in the cases where it was effective there were often inconsistencies between rooms in the same house. Important Note: Passyfier vents must not be used for providing ventilation to gas, oil, or solid fuel appliances.The external diameter of the tube is 104mm so the core should be cut larger eg. 4.25” (107mm). Permagard - Condensation Control Experts Tip: Apply a bead of sealant around the perimeter of the opening to ensure a water-tight installation. Installing Passyfier vents is relatively simple and can be done by most DIY enthusiasts without any professional assistance. The manufacturer provides detailed instructions with each vent, but here's a basic installation guide to help you get started. Kill any mould that exists on the floor, wall and ceiling surfaces with a good quality fungicidal wash before redecorating.