What are NZIB buildings?

While the concept of reducing energy consumption in buildings has been regulated by law in our country since 2018 [note], the term for reducing the ecological impact of buildings is a concept yet to be regulated in most countries, but it is extremely relevant in a scenario of climate emergency and the struggle for planetary sustainability.

The fact is that energy consumption is just one of the indicators to consider from a long list of impacts when discussing the life cycle of any built environment.

Beyond energy, all construction generates an impact on its direct surroundings that encompasses multiple factors capable of altering the balance and sustainability of ecosystems. If we want to maintain any chance of success in climate change mitigation and adaptation, it will undoubtedly be necessary to evaluate a building’s impact globally.

Thus, the concept of NZIB – Nearly Zero Impact Buildings was born, a term still without a specific definition within the regulatory framework of the construction sector, but one that has undergone years of evolution within the most internationally recognized independent certifications. The NZIB concept does not only consider energy consumption; it integrates a holistic view of the impact of a built environment on the natural surroundings and on people.

Preliminary concepts

To understand the framework in which the NZIB building designation appears, it is necessary to be clear on two key references that help us better understand its definition.

The first reference is the document The Limits to Growth, published in 1971, which discussed for the first time the impact of human beings and the goods or services they generate on the planet. This study, revised in 2012, is a key reference for understanding the impact of each of our actions on planetary sustainability and, in this case, on buildings, understood as complex machinery interrelated with their environment.

The second reference relates to the term Ecological Footprint, a tool that allows for the quantification of human consumption of the Earth’s productive resources in relation to their availability.

Limits to growth

In 1971, a group of scientists led by Donella Meadows from MIT drafted a report warning that population growth, combined with the constant increase in the consumption of planetary resources, was about to reach a breaking point.

This study was revised in 2012 by the same authors, stating that the physical limits of the planet had already been reached; for this, they used the ecological footprint tool that had first appeared in 1996. [1]

The ecological footprint

In general terms, the ecological footprint quantifies how much nature we have and how much we use. It is a tool that evaluates the human impact on nature and is expressed in global hectares.

The ecological footprint measures the impact of human activities on: grazing land, forest products, built-up land, cropland, fishing grounds, and carbon compared to their biocapacity. [2]

Based on these parameters, the area of biologically productive land necessary to maintain a good or service is measured, taking into account the resources required for its realization as well as the waste it generates.

Grazing and croplands provide us with food and fibers, forest products provide wood and paper, fishing grounds provide fish, built-up areas host the built environment, and carbon consumption provides energy. [3]

If we understand a building or built environment as a good or a service—and in practice, it could well be considered both—it will have an impact on the planet to the extent that it consumes resources and generates waste throughout all phases of its life cycle.

In this sense, the NZIB concept assesses a building’s impact based on its ecological footprint but also takes into account the people who inhabit it, understanding that any building must safeguard the health and well-being of its occupants, generating a positive impact.

From NZEB to NZIB

The NZIB building concept stands for Nearly Zero Impact Building. It is a concept complementary to NZEB buildings, or Nearly Zero Energy Buildings.

Unlike the NZEB concept, which refers to or quantifies only the energy consumption of a building, NZIB expands toward a more global vision and refers to the impact on the planet—closely related to the ecological footprint—and on people.

The fact is that the term NZEB, by referring only to the energy consumption of buildings, is focused exclusively on the impact of carbon emissions, a partial view of the total ecological footprint. [4]

For this reason, it is necessary to move toward the integration of the NZIB concept, a much more comprehensive model for analyzing the life cycle of a building and the elements that compose it.

CONSTRUCTION CRITERIA FOR AN NZIB BUILDING

In 2005, Professors Kibert and Grosskopf from the University of Florida’s Powell Center for Construction and Environment published a document [5] analyzing the new generation of green buildings, which they call Radical Sustainable Construction, and listed the five factors a green building must fulfill:

1. Integration with ecosystems and the environment.

According to Kibert and Grosskopf, one of the strategies that can yield the greatest long-term benefit in a green building is the extensive integration of ecosystems and landscape with the buildings.

The ecosystem surrounding a building has the potential to impact climatic conditions, well-being, water supply, production and waste generation, or environmental quality.

2. Construction with circular economy criteria.

One of the main challenges of sustainable construction is achieving high degrees of circularity. Today, only about 30% of a building’s construction materials are recovered at the end of its life cycle.

Achieving good management of material reuse, keeping material in circulation for as long as possible and recovering or recycling it at the end of its useful life, requires planning from the start of the project.

Furthermore, the life cycle of the material itself and its local origin must also be assessed, as it can generate a high impact on its direct environment throughout its useful life.

3. Application of passive design strategies and renewable energy.

While regulations are beginning to require standards for the efficient operational control of buildings, passive design—in which energy demand is reduced to a minimum and the rest is generated through renewable sources—is a field where much progress and awareness are still needed.

Basic strategies of bioclimatic architecture, such as proper orientation and solar gain, solar protection and cross ventilation, or the use of construction systems that guarantee thermal inertia (temperature accumulation) and good insulation and airtightness, are basic premises to be respected.

4. Water resource management.

Water management is an issue of increasing importance in the design of built environments. There is now a real risk that both climate change and the stress placed on water resources due to population growth will threaten the constant, low-cost supply we are accustomed to in industrialized countries and further complicate the survival of developing countries due to the scarcity of drinking water.

Furthermore, sewage networks are overloaded and must manage not only domestic wastewater but also rainwater that cannot filter into increasingly over-paved ground.

It is for this reason that the need to include water resource management within the project itself becomes clear, assessing options for total or partial self-sufficiency, greywater recovery, wastewater management, and rainwater harvesting or filtration.

This is a part of the project that must be addressed holistically, linked to the approach of the implementation strategy, bioclimatics, and the design itself, understanding the consumption and wastewater that will be generated and including vegetation consumption as a key factor.

5. Implementation of environmental quality management measures.

Indoor Environmental Quality (IEQ) is a very important indicator when designing spaces that guarantee the health of their occupants.

It is surely one of the factors that has gained the most relevance in the field of space design following the COVID-19 pandemic, during which the entire planet was forced to understand the quality of the spaces they inhabited and the well-being they generated.

Indoor Environmental Quality is determined by multiple factors, such as humidity, temperature, electro-climate, or pollutants released into the air (chemical and biological).

This quality can be affected by factors of the design and construction itself (orientation, solar gain, openings, quality of construction systems and their execution, HVAC systems, etc.) as well as by external factors such as the environment where the building is located or the elements and finishes installed by the occupants themselves.

These basic criteria are included in one way or another in most current building certifications, and all of them stem from their analysis throughout the building’s life cycle.

Once we have defined the five design criteria to reduce a building’s impact to zero, we must evaluate the success of the strategies applied. This is where a multitude of independent construction certifications appear. Certifications such as LEED, BREEAM, VERDE, or Passivhaus, among others, are created by private entities that audit built environments, granting a qualification based on the achievement of certain criteria.

Although each establishes its own methodology, it is possible to group the evaluation criteria into categories according to the impact they measure.

Factors defining the impact of an NZIB building:

1. LAND USE

2. BIODIVERSITY

3. Water Resource Management

4. POLLUTION AND WASTE

5. GREENHOUSE GAS EMISSIONS

6. INDOOR ENVIRONMENTAL QUALITY

7. HEALTH AND WELL-BEING