Buildings being made for people to live in, must take into account human comfort, while being designed. As a matter of fact, comfortable indoor environments increase occupants’ productivity, health and overall well-being.
In a serie of four articles, we will look into different performance indicators, such as visual comfort, acoustic comfort, air quality and thermal comfort, that can be designed and improved in order to promote occupant’s well being.
This article will focus on thermal comfort and how it contributes to a comfortable indoor environment towards green buildings and smart buildings.
What is thermal comfort?
When we think of thermal comfort, air temperature is the first variable that rings a bell to us. It is the feeling of being cold or hot. In fact, thermal comfort is the measure of heat transfer between the human body and its close environment. The air temperature will have a direct impact on people’s productivity. For instance, if people are too warm while working, they will start feeling tiredness whereas if people are too cold, they will be agitated and disturbed.
"A study of office workers showed a reduction in performance of 6% at 30°C and a reduction of 4% at 15°C, compared with a baseline of between 21°C and 23°C." - Saint Gobain
Thermal comfort encompasses different factors: environmental factors such as humidity, air speed, air temperature and physiological factors with body metabolism and clothing.
Environmental factors can be controlled and designed whereas physiological factors are solely dependant on the occupant’s behavior and physiology. To affect these physiological factors, governments like Japan for instance, have implemented the CoolBiz campaign, which aims to reduce electricity consumption in summer by encouraging employees to wear light clothes.
Surprisingly, thermal comfort is the subject of a cultural conversation. "In South-East Asia, some countries consider access to air condition a status in the society. It is the case in Indonesia and Vietnam, where using higher amount of air condition means being wealthier than people not using it", according to Eco Business.
So how can green design and smart technology improve thermal comfort?
Green design strategies to create thermal comfort
In tropical climate, thermal comfort is obtained by reducing temperatures to adequate levels and by increasing natural ventilation within the building. Green designs will favor a non energy demanding approach in order to take advantage of the natural surroundings opportunities such as wind. But using wind for sufficient natural ventilation in hot and humid climates is not only about opening a window.Green design aims to use passive strategies to facilitate natural ventilation by orienting buildings correctly, thinking of space layout from the start and sizing calculating the openings in order favor wind circulation, natural ventilation will be facilitated and its effectiveness increased.
Relying on natural ventilation is profitable as it uses natural wind resources, no energy required, to make our daily lives at home or at work more comfortable but it will also ensures that renewed fresh air will be provided within spaces.
“60% less energy is used by naturally ventilated buildings”, Breathing Buildings.
Thermal comfort is also better achieved when external thermal constraints are better controlled. The building’s envelope is the first blockage to solar heat gain which it can achieve through thermal insulation. Using proper insulation materials and thicknesses into buildings exterior walls has a considerable impact on our indoor environment. Not only will it save energy but also has the potential for good acoustic comfort (mettre lien article).
Certification rating systems such as LEED base their comfort criteria on assessment methods defined by the ASHRAE Standard 55 which takes on a percentage approach to judge if the thermal environmental conditions are acceptable to a majority of occupants.
Thermal comfort and smart buildings
New technologies and smart solutions also have a key role into people’s thermal comfort. With IoT, we can access real time data to analyse the thermal comfort of indoor spaces. In fact, some solutions have been implemented to optimize and control indoor thermal comfort.
Solution consisting of smart thermostats or controls, such as FIBARO Heat Controller helps predict occupants behaviour and calculate usual and preferred temperatures. This algorithm will enable to adapt the the indoor temperature based on the occupants daily rhythm.
For example, the smart device will reduce the energy consumption during working schedules and restart right before the occupants re enters their home.
Last but not least, some devices are capable of determining whether a building is empty or not, thanks to geolocalisation features of people’s mobile phones. This solution helps prevent useless air conditioning when the building is empty and so helps reducing electricity bills. It also monitors when a person will come back and can adapt the indoor temperature accordingly.
The combination of green design and smart technologies are able to create efficient and intelligent buildings by improving energy efficiency and analyze people’s behavior in order to improve their thermal comfort.