One of the most important qualities of good architecture is comfort. Among many parameters affecting human comfort within a given space, thermal comfort is most crucial and instantly sensed. The poor thermal condition also directly affects the efficiency of work and the well-being of the occupier, which makes it a critical consideration while designing a building.
There are no fixed ‘Universal standards’ or ‘recommended ranges of thermal comfort’ for building systems. The criteria, as well as design strategies, vary from region to region. Due to this, there can not be a definite way to achieve thermal comfort, yet the term widely can be defined as designing to achieve balance with the local climate, keeping human comfort as the focus. Here are a few major elements that should be considered while designing to achieve spatial thermal comfort.
Managing the parameters of the building envelope affects the interior thermal environment to a great extent. This makes efficient insulation one of the primary requirements to create a comfortable indoor condition. It reduces the amount of heat gained during the warm seasons and conserves heat during the cold months. To achieve maximum insulation both opaque and glazed areas of the envelope should be taken into consideration.
Solar Gain can be defined as the amount of heat generated indoor as solar rays are absorbed by the building. The amount of solar gain can be managed through the overall shape and orientation of the building as well as through proper calculations for the number and size of windows, opaque to glazed area ratio, percentage of heat reflection, and the type of shading devices. The building should be designed in such a manner to ensure minimum heat penetration during summers without blocking the passage of sun during winters and lower the dependency on mechanical interventions.
Thermal Inertia is the parameter controlling the speed of thermal conduction between the building and its surrounding. It majorly depends upon the primary material of construction and the type of structure, as it is in direct contact with the outer environment. The selection of material and structure should be done concerning the location, climate and function. Materials such as brick and stone are used in hot environments for their high thermal inertia to keep the interior cool for a longer period. While in cold regions, material such as wood which has low thermal inertia are used so that the interior heat up faster.
Managing the exchange of air and circulation with the outdoors is critical to achieving a comfortable indoor climate. This can be achieved by providing either mechanical or natural ventilation. Natural ventilation is most commonly used as a passive design solution for the flow of fresh air. Cross ventilation or stack effect promotes airflow due to the pressure difference. Stable air currents are required to release humidity and provide an in-filtered airflow. An airtight envelope thus is required to control the indoor thermal condition by managing the passage of air and heat.
Apart from these larger strategies, there are many design interventions. Such as creating an interior courtyard, provision of sunscreen, use of verandas and large eaves, use of water-bodies, vegetation, and green roofs. Designing for thermal comfort is a constantly growing field, and new ideas are shaping every day by revisiting the past techniques as well as developing new ones. But to design for thermal comfort efficiently, one has to have sufficient knowledge and familiarity with the local climate condition to correctly assess the sun movement, wind direction, and effects of rain and snow.