As technological advancements coincide with the global environmental crisis, people are moving toward a more sustainable lifestyle, promoting the notion of “Net-zero homes”. “Net zero” is the balance between the power a home needs and the renewable energy generated to match the demand. In the Indian context, this may be achieved in several ways, from using energy-efficient devices to designing considering environmental restrictions or Vastu (the science of directions).
Since the concept is still relatively new, the systems and products that go into a net-zero house are pricey but reimburse themselves over a period of time. In addition, it helps us improve the microclimate and lower carbon emissions, which is an investment for healthier living. In an attempt to enable that, governments and other institutions worldwide are also promoting the subject through various initiatives, thus shifting the focus of future designs and making them more energy conscious. Net-zero residential design and typical residential design.
The term “Net-zero” is often misinterpreted as a Zero consumption building. A building development achieves Net-zero status when the demand and supply of resources (e.g. energy, water, building materials, waste, etc.) are balanced. A typical building design often drives focused ease of construction and the least capital cost, which paves the way for the exploitation of resources and is often a short-term saving strategy. Much like a living organism, a Net-zero house is self-sustainable and one with nature. Achieving balance has been the way of nature, and if we can do so with the buildings we construct, we will be in tune with the natural ecosystem. In India, the sense of belonging to nature can be termed as the fundamental Net-zero approach, many of which are based on “Vastu” principles and eco-sensitive design. Demand and scope for Net-zero residential design Net-zero residential design is consistently gaining attention while also being prevalent in specialized scientific buildings often constructed as exemplary projects to make a mark. With cut-throat competition in the real-estate business and the constant pressure to create value in their offerings, developers across the country are making an effort to join the bandwagon on sustainability. Green building rating is no longer a USP; Net-zero is the way ahead.
As far as scope is concerned, net-zero will soon become a mainstream design criterion in housing projects, which is a stronghold of the real estate industry in India. Environmental consciousness is an indispensable virtue for the future, and houses are relatively less energy-intensive since there is much lesser occupancy per unit area of a building, making them an accessible proposition for Net-zero. Hence, Net-zero will be a USP for developers and real-estate investors and will be attractive to the current generation of buyers.
Ways to make Net zero residential design affordable
The trick to the affordability of Net-zero is stripping the building’s energy/water/material requirement down to the bare minimum. This way, not only do we achieve energy efficiency but at the same time minimize the building’s generation/recycling requirements to offset the said demand. Reducing the embodied energy, or in simple terms, the dead load comprising the structure of the building is also an essential aspect of addressing affordability. Reducing embodied energy majorly contributes to reducing capital costs. The Indian government has also been lately promoting novel renewable energy technologies using incentives and funding for the common person, which go a long way in the affordability of these systems critical to achieving Net-zero.
Strategic sustainable methods
A net-zero residential design approach is different from the practices of designing for just a Green Building Rating in the sense that the building must use Net-zero energy & water. It needs to recycle & replenish in equal amounts as it consumes, creating significant pressure on stripping off the building’s load/demand to the extent possible as well as designing to allow for micro-generation. With the advent of EV transport, residential power consumption will shoot up, and so will the need for generating it through renewable sources.
Houses offer a massive array of possibilities to achieve sustenance. Significant energy savings are achieved by improving the R-Value of the facades, say for a tropical climate zone and densely populated cities. Houses are occupied more during the night than the day, and better insulation keeps out the daytime heat, preventing the building’s thermal mass from collecting heat which gets radiated at night. Harnessing renewable energy sources such as solar, wind, and geothermal for generating power or building heating/cooling requirements significantly reduces carbon emissions by offsetting energy demand.
Housing projects must be designed to respond to climate and context with energy conservation measures such as optimal building orientation to maximize natural light and ventilation, optimum shading for windows and balconies, SRI paints on the roof and exterior walls for high heat reflectivity, high-performance glass on windows and balcony to reduce heat ingress from the building envelope, and energy-efficient lighting and equipment. Vertical circulation in the residential towers must be aided by Variable Voltage Variable Frequency (VVVF) elevators that use less energy. Other unique features include low-flow water efficient fixtures, rainwater harvesting, and sewage treatment plant that drastically minimizes the water demand by 74% when compared to conventional buildings. Sustainable strategies such as waste segregation, composting, and waste recycling through a resource recovery centre and vendor tie ups essentially lead to a zero e-waste project.
Way Forward
The approach to architectural design will need to become highly performance-driven. Green spaces will require much more functional purposes than just manicured gardens, as they require the least amount of water for irrigation, maximizing power generation & rainwater harvesting opportunities, all with the least amount of intervention to natural features. Daylit spaces must be achieved to the maximum, and artificial lighting must be designed to the minimum required illumination levels only. Building services must revolve around the least power & water consumption, as well as alternative power/air-conditioning sources, which should be integrated accordingly.
Creating Net-zero buildings on a large scale will require a road map, especially for the affordability and skill development aspects. A fundamental virtue of cultivating a sustainable approach to residential design is that everyone does their bit to make it all happen and incorporates energy-efficient activities on a day-to-day basis to create a significant impact. Schools need to teach Net-zero etiquette to the children to set a foundation for the upcoming generations as well.
A passive design will be the starting point that will require designers, sustainability experts, energy modelers, and engineers to come together to facilitate a holistic design process. In addition, developers, development authorities, and environmental policymakers will need to incorporate a roll-out plan for Net-zero developments.
Arpan Dalal is Project Head, Developer Spaces, Edifice Consultants.