On average we spend around 90% of our lives indoors, and breathe around 12,000 litres of air every day. We can survive around thirty days without food, up to four days without water, but only minutes without air.
Various factors determine resident comfort and health including air temperature, relative humidity (RH) and air velocity and pressure. Clothing, activity and metabolic rate may also influence how a person is feeling within a space; therefore the purpose of the room helps guide solution design. For example, the focus for a living area would be on air temperature, air velocity and pressure, while for shower and bathroom areas it would be ventilation rates, and home gyms would include a closer focus on relative humidity.
Indoor air quality is also directly correlated with a resident’s comfort, health and wellbeing. Factors include Carbon dioxide, Volatile Organic Compounds (VOCs), Pathogens and Particles. These elements may be already present within our homes, or may enter via the mechanical supply air system. It is essential that they are monitored, diluted and removed by a fresh air supply and extract system with effective integral filtration.
Room temperature generally refers to the ‘ambient’ temperature of a room, which is how warm or cold the air is. The average ideal room temperature for comfort of the occupant is around 20°C; however, different rooms may be more comfortable at (and indeed may require) different temperatures. As the human body is very sensitive to temperature, cold air will cause a tension in our muscles and a reduction in our immune systems.
Air humidity levels are temperature-dependent and also determine the level of moisture we are breathing in. There is conclusive scientific evidence that an air humidity of 40 – 60%RH has significant benefits for human health, as this is the optimal level for our respiratory immune system and is thus highly effective at reducing the spread of seasonal respiratory illnesses. Low humidity causes dry skin and eyes, and increases infection rates and asthma attacks.
Accurate air dilution and flow patterns are required for sufficient air supply and removal of contaminated air; however, air velocity must be controlled to reduce drafts and evaporation chill. Additionally, active pressurisation of indoor spaces by control of supply and extract volumes can prevent ingress of air from undesirable external environments.
We exhale large volumes of CO2, and evidence indicates that at concentrations between 1,000 and 2,000 parts per million (ppm), drowsiness and headaches are more likely to occur. Indoor CO2 level is a strong indicator of increased occupancy and limited air exchange, which also brings the risk of high levels of VOCs and pathogens and particles.
Paints, varnishes, softeners, perfumes and cleaning agents are all organic compounds and sources of VOCs. Even low concentrations can irritate the eyes, nose, or throat, and contribute to both short and long-term health issues. Exposure levels are typically 2 to 5 times higher inside a home than outside.
Pathogens and particulate matter (PM) penetrate deep into the lungs, causing sickness, allergic reactions, asthma attacks, lung infections and lung cancer. In order to maintain optimum indoor air quality, fresh air must be brought in through a demand-based air-handling system with enhanced filtration, where monitoring systems have an important role in creating a healthy environment.
Discreet air conditioning for this terraced 4-bed mews house in a small courtyard just off Fulham RoadFind out more