Architecture is a transdisciplinary field. It incorporates principles and knowledge from several other disciplines to ensure a built structure functions as intended. This fundamentally involves considering the context in which a building is placed, including its immediate surroundings, such as neighboring structures, local biodiversity, and climate. Essentially, architecture only exists within a particular context. When we expand this context to a broader scale, it becomes what we commonly refer to as the "environment."
Architecture should not be disconnected from the environment, and sound design principles have always aimed at optimizing a building's bioclimatic performance. As modernity and technological progress advanced, we gained the ability to artificially regulate this performance, partially disconnecting the building from its natural environment. However, the current environmental crisis has underscored the urgent need to revisit and promote what we now term "passive design." In essence, passive design aligns with bioclimatic architecture, utilizing natural conditions to regulate a building's temperature and energy use. Ensuring environmental comfort is a significant factor in a building's overall effectiveness, and in light of the imperative for environmental sustainability and regeneration, the key question facing the field of architecture and its stakeholders is: Can passive design effectively reduce the human carbon footprint?
Passive design is an approach that relies on harnessing natural conditions to reduce the need for artificial or mechanical climate control. This entails optimizing a building's layout, materials, openings, and orientation to make the most of natural elements, ultimately enhancing environmental comfort. Applying these strategies makes individual buildings more environmentally friendly and significantly reduces the overall energy consumption when widely adopted.
Fundamental principles of passive design include selecting openings that enable sunlight to enter during colder months and provide ventilation in hot climates. It is worth noting that the construction industry ranks as a significant contributor to CO2 emissions, with the production of its raw materials accounting for a substantial portion of these emissions. The notion of a "carbon footprint" measures the emissions generated throughout the entire life cycle of any entity, whether it's a living organism or an inanimate object, that contributes to the environmental impact on our planet.
Construction heavily relies on manufactured and processed materials with a substantial environmental footprint, often without proportional benefits. The fields of knowledge related to it must develop more environmentally responsible techniques and materials. Strategies like utilizing prefabricated materials, repurposing waste materials, and sourcing local resources should be integral to efforts aimed at mitigating the environmental impact on our planet.
Passive design has a positive environmental impact by reducing the need for active HVAC systems, which rely on finite, non-renewable resources. Notably, heating and electricity are accountable for approximately 19% of indirect greenhouse gas emissions. Therefore, adopting passive design principles can significantly lower this emission rate. When we decrease our dependence on electricity and environmental heating, we alleviate the burden on these systems. As a result, this reduction in demand leads to less use of fossil fuels, the primary energy source for producing and delivering these services.
Cross ventilation is a passive method for natural air conditioning. The building's placement should consider local conditions, such as harnessing prevailing wind currents during hot summer months to make the most of this technique. Additionally, strategically positioned openings near the ceiling act as outlets for hot air that accumulates near the upper areas, effectively reducing indoor temperatures. Insolation, the exposure to sunlight, works on a similar principle. It involves aligning the building's orientation with the ground to ensure direct sunlight entry, particularly in colder seasons like winter. It's also crucial to factor in how sunlight affects construction materials. These materials should possess thermal inertia compatible with the desired effect, which means they can absorb heat during the day and gradually release it at night, or facilitate these heat exchanges.
In addition to bioclimatic strategies focused on how we use and occupy built spaces, a significant portion of greenhouse gas emissions is associated with construction materials production. For instance, the manufacture of cement and steel involves the burning of fossil fuels. Hence, it is imperative to prioritize research and development efforts to create sustainable and renewable alternatives to materials like cement and steel. Green roofs are a vital component of the construction system, seamlessly harmonizing with passive design. Additionally, the creation of construction materials using waste as their primary raw material and ensuring recyclability brings these materials closer to a natural life cycle, which also includes environmentally responsible disposal.
Efforts to prioritize passive design depend on the architects' approach, ideally right from the project's inception. A prominent illustration is the Brazilian architect João Filgueiras Lima, also known as Lelé. He gained recognition for his extensive use of bioclimatic strategies, with a strong emphasis on optimizing ventilation, utilizing cost-effective materials, and implementing efficient waste management practices during construction and manufacturing. His widespread use of prefabricated construction methods expedited the building process while maintaining a cleaner work environment. Additionally, Lelé incorporated a cross-ventilation system, sometimes facilitated through exhaust fans and ducts, as a passive design application, enhancing the long-term cost-efficiency of buildings. Particularly in healthcare settings, integrating natural air conditioning systems also reduces the risk of disease transmission and infections.
Long-term sustainability is a concept championed by architect William McDonough, a prominent figure in cradle-to-cradle architecture. McDonough staunchly advocates ecological compensation in his projects, exemplifying a net-zero approach to mitigate the environmental impact of new construction. An illustrative case from 1989 involved McDonough winning a competition in Poland for a business tower. In addition to the building design, the architect stipulated an area of 26 square kilometers of trees, a measure intended to offset the energy consumed during the construction and operation of the building.
When combined with renewable energy systems, passive design significantly enhances a building's performance. It makes the structure more self-sufficient in terms of energy, and in cases where passive measures alone may not suffice, cleaner energy sources can supplement the needs. Notably, according to the United Nations, the solar radiation reaching Earth surpasses our human electrical demand, indicating a more environmentally responsible way to live comfortably. Throughout a building's lifecycle, passive design also reduces the maintenance requirements because it relies less on artificial air conditioning. This, in turn, minimizes the likelihood of disruptions to the building's infrastructure and systems, benefiting both occupants and builders.
While passive design is valuable, it alone may not address all aspects of a project. Despite the significant emphasis on optimizing facade design and orientation, new construction projects are often influenced by neighboring structures and urban regulations that can impose constraints, potentially limiting the ideal building placement. Additionally, the accelerating global temperature rise impacts the effectiveness of traditional passive design strategies. As climate conditions grow increasingly erratic and uncertain, relying solely on passive design may not always effectively address extreme weather challenges. Consequently, it is imperative to explore design and construction approaches that consider environmental factors and mitigate humanity's impact on the planet. This involves assessing the energy sources employed, enhancing building performance, and integrating all these elements cohesively within the project.
It's essential to recognize that passive design is just one element within a broader system, contributing to environmentally responsible and regenerative architecture. Understanding and utilizing natural conditions is fundamental knowledge for those involved in construction. It is equally crucial to consider the materials used in the project, the urban infrastructure supporting the building, and its position within the city. In essence, it's a matter of scale. Individual measures are significant as they indicate a shift in approach, but given the substantial environmental impact of human activity, our collective efforts must match the scale of the challenges we face.
This article is part of the ArchDaily Topics: Decarbonize Architecture presented by Holcim.
Driven by its purpose to build progress for people and the planet, Holcim is decarbonizing building, while improving living standards for all. Holcim empowers architects and developers across all regions to build sustainably. This series explores how cities of the future can be low-carbon, circular, and resilient.
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