Net Zero Energy Buildings: All You Need to Know.

We’ve all heard the joke - “Why is it called a building when it’s already built?”

Looks like there is an answer.

What’s built is the structure. What’s building is CO2 emissions. Wait, what?

If you’re intrigued, a dive into the world of Net Zero Energy Buildings would be a good start.

Net Zero Energy Buildings All You Need to Know. BIM Services
Net Zero Energy Buildings: All You Need to Know.

What are NZEBs?

Net or nearly zero energy buildings (NZEB) are highly efficient buildings that use renewable energy sources to meet their energy demand. The total amount of energy used by the building on an annual basis is equal to the amount of renewable energy created on the site.

Such buildings have a two-pronged approach. First, they reduce the demand for energy using efficient design & technology. Then, they use renewable sources of energy to meet the residual demand.

Why NZEBs?

Global warming & climate change are running riot. Thawing ice, rising seas, chaotic weather, frequent disasters, the list goes on. Sustainable living might soon be not a choice, but a necessity.

For a cleaner and greener future, it is important to act. More so, in the right direction.

Buildings and construction constitute almost 40% of global carbon emissions. Buildings consume energy equivalent to 36% of the world's total energy consumption. Also, the building sector accounts for about 55% of the global electricity use. This is enough statistics to mind what we build or have built.

If you’re wondering, the major areas of energy consumption in buildings are heating, ventilation, and air conditioning (HVAC); lighting; major appliances (water heating, refrigerators, freezers, dryers); and miscellaneous areas including electronics - in that order.

It’s only obvious that Net Zero Energy Buildings have received such heightened attention lately.

Zero Energy Buildings are great for the environment. They are reliable and affordable, while improving energy security, increasing comfort for the occupants, and minimizing operating and maintenance costs.

There’s also the money factor. Policies like Net Metering & Feed-In Tariff allow building owners to send the excess energy produced back to the grid, and be compensated for it. Also, incentives and tax benefits by government bodies make NZEBs all the more appealing.

Zero Energy Buildings - Approach

If you recall, NZEB’s first reduce energy demand using design & technology (passive strategies), and use Renewable Energy to meet the residual demand (active strategies).

Passive Strategies:

The passive strategies include Passive Sustainable Design & Energy Saving Techniques. It is concerned with architectural design techniques and energy-efficient technology respectively.

Passive Sustainable Design:

The main considerations here are the building’s geographical (latitude, longitude, altitude) and meteorological (temperature, humidity, sunshine duration, wind speed) factors. These factors are extensively studied and applied in the following:

• Building Orientation

• Fenestration (the arrangement of windows in a building)

• Cool Roofs & Outdoor Surface Reflectance

• Shading

• Interior Finishes

• Thermal Insulation

The goal here is to achieve the ideal building geometry, natural lighting, and natural ventilation.

Energy Saving Techniques:

• Use of high efficiency fluorescent or LED lighting

• Lighting controls such as occupancy and dimming sensors

• Efficient HVAC system for heating and cooling

• Automatic ON/OFF controls for computers and office equipment

• All other energy-efficient appliances

There’s so much tech to play around with. The choices are made based on preference and budget.

Active Strategies:

Once the building’s energy demand is reduced using passive strategies, the residual load can be met using the active strategies, i.e., Renewable Energy. There are two components to this: Renewable Energy and the back-up system for RE.

Renewable Energy:

This is a key component of NZEB. Five types of RE mostly used:

• Solar PV system

• Solar thermal system

• Geothermal system

• Wind turbine system

• Biomass

The choice depends on the bio-climatic conditions surrounding the building.

Back-up system for RE:

These are systems for the effective application and management of Renewable Energy. Commonly includes:

• Fuel cell

• Energy storage system

Zero Energy Building Vs Green Building

Green buildings focus on reducing or eliminating a building’s impacts on the environment, by using less water, reducing waste, using recycled building materials, quality of life of occupants, indoor air quality, and environmental adaptability in design, construction, and operation. Leadership in Energy and Environmental Design (LEED) is a popular green building certification program used worldwide.

Illumine-i is a leading Green Building Consultant providing a range of services like energy audits, energy modelling, building simulations, LEED certification, etc.

Zero energy buildings, on the other hand, achieve one key goal of exporting as much renewable energy as it uses over the course of a year; reducing greenhouse gas emissions. Zero energy buildings are not necessarily green buildings.

Net Zero Energy Buildings All You Need to Know. BIM Services
Net Zero Energy Buildings: All You Need to Know.

Case study

SIERRA's eFACiLiTY® building in Coimbatore, India, is a software development center. It is India’s highest ranked platinum certified building.

The building envelope is built with 18-inch thermal mass walls, high-performance reflecting windows, and cool roof tiles, as well as foam concreting, to minimize thermal load and hence lower energy consumption.

For air conditioning, sensors are placed strategically throughout the building, thereby aiding in the regulation of temperature and fresh air supply. Only the cleanest air reaches workstations because of triple filtration.

100% LED lights have been used leading to a 0.26 W per sq. ft. lighting power density, which is 80% better than ASHRAE-defined standards.

Waterless urinals, high-efficiency sensor faucets, reuse of treated water for flushing, and reuse of stored rainwater for residential use can save up to 89 percent of water.

The building has installed solar renewable system to meet the energy demand. This includes 60 KW rooftop solar PV, 4.3 KW Amorphous Silicon thin-film Building Integrated Photovoltaic (BIPV) glass panels which meets 80% of the energy demand.


Net Zero Energy Buildings are crucial to our collective efforts towards a sustainable future. Buildings can incorporate energy efficient and renewable energy generation practices during design, construction, and operation to reap a variety of benefits, as well as contribute to the greater environmental good.

It makes good sense to be thoughtful about our buildings that have been built, and what they might be building.