Design strategies for intelligent, modern buildings should also promote healthy and comfortable indoor environments.
A healthy building provides:
- Ventilation and good indoor air quality
- Good water quality
- Prevention of moisture, mold and pests
- Noise reduction
- Natural lighting and pleasant views & aesthetics
- Reliable heating & cooling
- Privacy & Security
- Manageable costs
- Low on waste and pollution
The built environment is having a significant effect on the occupants’ physical and psychological well-being, health and performance.
Occupant Satisfaction and well-being
Well-being and occupant satisfaction cannot be achieved just by meeting minimum requirements, both not only depend on physical but also on psychological factors. The WHO’s definition: “Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”
Well-being depends on the overall perception of the surrounding environment and other conditions, including climate and weather conditions, building related factors as design, disposition and control, and individual characteristics of the occupants (like gender, age, type of work).
Ventilation and good indoor air quality
Standards related to Indoor Environmental Quality (IEQ) define humidity, ventilation rates and exposure limits for air pollutants. Measurements of indoor air quality are based on the intensity of the ventilation. Indoor air quality can either be controlled naturally (windows) or artificially (air conditioning systems).
Building-related illnesses related to poor indoor air quality are: CO intoxication, allergic diseases like asthma and rhinitis, sensitivity to chemicals and respiratory illnesses. The effect of poor indoor air quality further depends on intensity, length, and source of noxious exposure.
Ventilation belongs to the fast reacting systems, so changes can take place immediately. Indoor air quality is closely related to thermal comfort.
Prevention of moisture, mold and pests
Moisture creeps into you building, working its way through walls and causes all kinds of bad news like mold, fungus and spores.
To achieve overall satisfaction with the indoor thermal conditions, heating, cooling and air conditioning systems are used to control parameters such as temperature, humidity and air velocity. Technologies controlling thermal comfort are slow-reacting technologies, meaning their adaptation takes some time.
Three variables influence the thermal comfort perception: the climate, the nature of a building (and its services) and time (defining the rate at which the changes occur to which one has to adapt). Increased temperature leads to a higher concentration of harmful substances in the air originating from fixtures, meaning that there’s a high dependency between temperature and air quality.
Acoustic quality and noise reduction
Acoustic comfort is often described as an acceptable level of noise. But the perception of sound is a more complex issue, depending on sound intensity and its temporal and spectral features, as well as on someone’s activity, state of mind, and expectations. Noise is defined as “the sound occurring within the frequency range of the human hearing which disturbs silence or an intended sound perception and results in annoyance or endangers the health”. Sound can be defined as a wave motion from a sound-producing object. It varies according to frequency and pressure.
Acoustic quality “is the degree to which the totality of the individual requirements made on an auditory event are met”. It comprises three different kinds of influencing variables: physical (sound field), psychological (auditory evaluation) and psychoacoustic (auditory perception), so it is multidimensional. defined acoustic satisfaction “as a state of contentment with acoustic conditions; it is inclusive of annoyance, loudness, and distraction”. However, there is no standard definition neither for acoustic quality nor acoustic comfort/satisfaction. A good acoustic environment is typically associated with the isolation of unwanted sounds and presence of pleasant sound.
Acoustic quality in buildings is influenced by sound insulation and sound absorption. Sound insulation of a building’s shell, roof and windows is important in terms of the protection of the building interior from unwanted outdoor noise (e.g. traffic noise). Sound insulation of floors, walls and doors needs to be considered once indoor sources (neighbors’ noise, air-conditioning units) are present. Once a room is insulated, room acoustic aspects come into attention. Sound produced inside a room (such as restaurant ambiance, classes at school) can be enhanced due to multiple reflections. Volume, shape and the total amount of sound absorption play a role.
Noise causes distraction, stress, annoyance, leads to fatigue or can damage your hearing. Even lower sound levels might affect human health once a person is exposed for a long time, causing insomnia. For the indoor sound environment, sound level and speech privacy belong to be the most important factors. Finally, neighbor noise might also cause health problems. Chronic exposure to noise can cause a variety of health problems, such as hearing impairments, hypertension, cardiovascular problems, sleep disturbances and annoyance. Noise exposure can also have psychological effects such as stress and decreasing cognitive performance and attention.
Visual Comfort: Natural lighting, pleasant views and aesthetics
Well-being induced by the visual environment: a well-designed lighting system provides adequate illumination to ensure safety and enable movement. A significant part of the illumination should be provided by daylight, offering a view to the outside, which contributes to the psychological well-being of the occupants – a direct relationship between natural light and health has been proven numerous times. Insufficient light can disrupt the biological rhythm, which can have an impact on health, safety and performance.
For decades studies have shown a positive effect of daylighting on health. A statistically significant relationship between view type, view quality, social density, and perceived discomfort has been reported. This is also supported by findings of the HOPE project of positive statistical correlation between view and comfort. These have been identified, to have a positive effect on human psychology, sleep quality and mood. Some other relationships between luminous conditions and occupant satisfaction can be found.
Lighting and solar shading systems are considered fast-reacting systems, a change in conditions can happen almost immediately. They are also low-energy consumption systems. Still, it can account for up to 25% of the total building’s used energy – here, solar panels lead a major reduction in costs.