Ventilation & Indoor Air Quality (IAQ)

Ventilation and indoor air quality - VMC, AHU, filters, purifiers

Thermal comfort is not enough if the air we breathe is stagnant and polluted. With modern buildings becoming increasingly airtight (due to strong insulation and new windows), Indoor Air Quality (IAQ) is the top priority for our health.

In this section we analyse everything about proper ventilation: from simple bathroom exhaust fans and natural ventilation, to cutting-edge Heat Recovery Ventilation (VMC) systems and Central Air Handling Units (AHU). Learn how to control humidity, CO₂ and how to filter dangerous pollutants.

Natural, Local Ventilation & Extraction

The first line of defence against odours and humidity. Before moving to complex mechanical systems, let us see how proper natural air management and basic local extraction devices (kitchen, bathroom) can immediately improve the atmosphere of your home.

Cross-Ventilation & The Stack Effect.

How to renew the air in your home in just 5 minutes, exploiting pressure and temperature differences, without freezing the walls in winter.

Bathroom Exhaust Fans: Selection and correct placement.

Forget simple switches. A guide to automatic fans with delay timers and built-in humidity sensors for complete mould protection.

Natural ventilation infographic - cross-ventilation, exhaust fans, range hoods

Kitchen Range Hoods & Makeup Air.

Why a very powerful range hood can "suffocate" your energy fireplace. How to correctly calculate the volume (m³/h) and why the air that exits must re-enter from somewhere.

The Limits of Natural Ventilation in modern homes.

Open windows or machines? Why modern, perfectly airtight windows and external wall insulation make continuous mechanical ventilation literally mandatory.

Central Air Handling Units (AHU)

The heavy artillery of ventilation, designed for hospitals, hotels, shopping centres and industries. A deep mechanical engineering look at systems that manage enormous air volumes 24 hours a day.

What is a Central Air Handling Unit (AHU)?

A deconstruction guide for new engineers. We analyse the basic parts: supply/exhaust fans, water coils, filters and sound attenuators.

Commercial Kitchen Ventilation (Food Service).

The strict legislative requirements: hood sizing, grease capture filters, odour removal systems (Carbon/Ozone) and duct fire protection.

AHU infographic - mixing boxes, VAV/CAV systems

Mixing Boxes & Energy Savings.

How modern AHUs smartly mix fresh outdoor air with return air from the building, dramatically reducing heating and cooling loads (ASHRAE Standards).

VAV (Variable Air Volume) vs CAV (Constant Air Volume) Systems.

Technical differences and applications. How VAV systems adjust air supply according to the number of people in a meeting room or office.

Heat Recovery Ventilation (VMC / HRV / ERV)

The technology that changed the game in residential buildings and is the "heart" of Passive Houses (Passivhaus). How can we keep windows hermetically sealed, indoor air perfectly clean, and energy consumption at zero?

What is Mechanical Ventilation with Heat Recovery (VMC)?

The magic of the heat exchanger. How you bring fresh, oxygenated air into your home without the winter freeze or summer heatwave entering.

HRV (Sensible) vs ERV (Enthalpy Exchangers).

Which technology to choose? See why ERV systems have the advantage in the Greek climate, as they recover not only temperature but also humidity.

VMC infographic - HRV, ERV, central vs decentralised, summer bypass

Central vs Decentralised Heat Recovery Systems.

What suits your project? We compare central units with ductwork (for new builds) with wall-mounted standalone units (ideal for simple room renovations).

What is Summer Bypass (Free Cooling)?

How the recovery unit smartly bypasses the heat exchanger on summer nights, directly introducing the night coolness to drop the home's temperature completely free.

Antibacterial Ducts & Plenums.

Installer's guide. Special plastic residential ventilation networks (with silver ion coating) that never catch mould and do not require continuous cleaning.

Filtration, Purification & Humidity Control

City air is polluted, but the air inside our homes is often 5 times more contaminated! Learn how to control invisible enemies (VOCs, germs, mould) to breathe cleaner than on a mountaintop.

Sick Building Syndrome (SBS) & CO₂ Levels.

How oxygen deprivation causes drowsiness and headaches. Learn how smart CO₂ sensors detect poor air quality and trigger immediate ventilation.

VOCs (Volatile Organic Compounds) & Formaldehyde.

The invisible danger. How new furniture, carpets, cleaning products and paints silently pollute your home and how we effectively combat them.

Filtration infographic - G4-HEPA filters, CO₂, VOC, humidity

Ideal Humidity (40-60%): Dehumidifiers & Humidifiers.

The golden mean of comfort. Why we need dehumidification in summer (Dry Mode/Dehumidifiers) and why heating in winter often requires a humidifier.

Air Filter Guide (From G4 to Absolute HEPA).

What each filter captures (from coarse dust to viruses and pollen) and why we cannot install HEPA filters everywhere without "suffocating" the machine (pressure drop).

Air Purifiers: Myths and Truths.

Ionisers, UV-C Lamps and Activated Carbon. An honest look at which systems have a real medical effect against allergies and which are simply marketing.

Main HVAC Guide

Return to the full heating-cooling guide for energy production, hydraulic networks, emission systems, automation and energy design.

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