The Role of Givoni Bioclimatic Chart in Shaping a Sustainable Design

Introduction

As the world continues to emphasize sustainable building practices, architects and designers seek new ways to integrate environmental considerations seamlessly into their projects. A useful tool for this purpose is the Givoni`s Bioclimatic Chart which, based on the climatic zone, informs on the active and passive heating and cooling strategy to achieve the optimal comfort zone for occupants and minimize the use of energy for air conditioning of indoor spaces.

The term “bioclimatic” refers to an architectural and urban planning approach that integrates the local climate and natural elements to create energy-efficient and sustainable buildings. It involves using passive design techniques that work in harmony with the surrounding environment, such as optimizing building orientation use of natural ventilation, as well as passive heating and cooling.

The use of the diagram in the early stages of design guides architects toward building envelope strategies that can reduce the building’s energy consumption by minimizing the use of cooling and heating systems, thereby lowering its ecological footprint while simultaneously enhancing the occupants’ well-being.

The article describes how to interpret Givoni’s Chart and implement its recommendations into a sustainable design.

Navigating the Givoni Bioclimatic Chart

Givoni`s Bioclimatic Chart allows us to analyze thermo-hygrometric conditions according to the prevalent outdoor environment.

Thermo-hygrometric refers to the comprehensive analysis and measurement of temperature relative humidity (%RH), which describes the amount of water vapor in the air.

The graph is divided into two axes where the vertical axis describes the specific humidity g/kg and the horizontal axis describes the dry bulb temperature.

In the diagram, the curved lines represent the relative humidity. It is expressed in percentages, as it corresponds to the ratio of water vapor contained in the air to the water vapor required to saturate one kilogram of dry air at dry bulb temperature.

In addition, 14 color-coded zones are overlaid on the diagram, each corresponding to a design strategy according to specific climatic conditions:

1. Comfort zone;
2. Comfort zone permissible;
3. Heating Internal gains;
4. Passive solar heating;
5. Active solar heating;
6. Humidification;
7. Conventional heating;
8. Solar protection;
9. Cooling high thermal mass;
10. Evaporative cooling;
11. Cooling high thermal mass with night cooling;
12. Cooling natural and mechanical ventilation;
13. Air-conditioned;
14. Conventional dry;

By superimposing the characteristic points of a particular climatic zone on the Givoni`s bioclimatic diagram, resulting from the intersection of the outside air temperature and the specific air humidity, an overview of climatic conditions is obtained. The concentration of these points on specific areas of the graph allows the choice of design strategies to be applied to the building, to achieve optimal indoor comfort, while reducing the use of energy.

The main considerations of the Givoni Bioclimatic Chart

Depending on the climate (warm, hot, cold, humid, etc) the chart identifies different strategies, systems, and mechanisms to arrive at the optimum comfort zone with minimum energy required.

In cold climates, where temperatures hover around 10 degrees centigrade and fall in zone 4 of the table, passive solar design is recommended, optimizing orientation and adjusting the window/wall ratio to take advantage of solar heat gain during winter, thus reducing dependence on heating systems and minimizing energy consumption.

If we should be in “Zone 5” instead. , the table will recommend active solar heating. This means that the thermal conditions inside the building are influenced by an active solar heating system that uses solar energy to actively generate heat.

A solar active heating system is used in zone 5, which may include solar panels, solar thermal collectors, or other technologies that capture solar energy and convert it into heat that can be used for space heating. This solar active heating system can be integrated with an air or fluid distribution system to distribute the heat generated to the different zones of the building.

For buildings situated in hot and sunny climates (Zones 8 & 9), natural ventilation and effective shading systems, such as external louvers, overhangs, and deciduous trees, are recommended to prevent excessive solar heat gains, maintain comfortable indoor temperatures, and reduce the need for cooling.

In arid climates (Zone 10), water sources can be utilized for indoor cooling and passive cooling techniques can be integrated to create pleasant indoor spaces.

In tropical climates (Zones 11& 12), architects can implement natural ventilation and passive cooling strategies, utilizing shaded outdoor spaces and material moisture-absorbing (Calcium chloride) materials to mitigate high temperatures and humidity, providing a comfortable indoor environment.

In temperate climates (Zones 1,2,3,8 & 9), Givoni`s Bioclimatic Chart encourages architects to incorporate natural ventilation strategies, including operable windows, stack ventilation, and cross-ventilation, promoting airflow and enhancing indoor air quality for improved occupant comfort.

Furthermore, the table highlights the importance of internal thermal mass in the interior. Materials with a high thermal mass, such as concrete or stone, can store heat or cool and then gradually release it over time, contributing to stable indoor temperatures in different climates.

Conclusion

The Givoni Bioclimatic Chart assists architects and urban planners in creating sustainable and energy-efficient buildings. By aligning designs with local climatic conditions, buildings can reduce their ecological impact while ensuring occupants’ comfort and well-being. Emphasizing passive design techniques leads to decreased energy consumption, mitigating greenhouse gas emissions and climate change. Bioclimatic principles prioritize natural ventilation, daylighting, and temperature control for a healthier indoor environment. The integration of passive design elements also results in cost savings, benefiting both building owners and occupants. Embracing the Givoni Bioclimatic Chart contributes to creates a sustainable building (now) and aligns with the global push towards a greener future, propelling us towards a more resilient and planet-friendly (tomorrow).