A net-zero energy building (NZEB) can be defined as a building that produces as much energy as it consumes when measured at the site. These buildings provide high performance by taking a significant amount of energy from renewable sources produced on-site or off-site.
Several design tools and applications are available in the market to help designers in the residential and commercial sectors design their buildings as net-zero energy buildings.
In the United States, California and New York are more into the construction of net-zero buildings, thus contributing less than 10% of the total emissions in the U.S.
To achieve efficient net-zero energy buildings, the first step is to follow the design standards to balance the net energy consumed to achieve efficient net-zero energy buildings.
The next step is to stimulate energy consumption using various energy modeling techniques and tools to optimize building factors like orientation, temperature, humidity, overall system efficiency, etc.
This article discusses the three main principles followed by designers to achieve a good net-zero energy building design, that is:
- Building envelope measures
- Energy efficiency measures
- Renewable energy measures
1. Building Envelope Measures in NZEB Design
A high-performance building envelope constitutes all the elements of a building’s outer shell that allows high-level control over different variables within the structure, such as the temperature, humidity, air, noise, and energy expenditure.
A high-performance building envelope system is one of the elements integrated into Net Zero Energy Buildings (NZEB) design, where the main objective is to minimize energy consumption.
Building orientation has an important role in minimizing HVAC loads. In addition, shades/overhangs are used to reduce direct sun rays. Providing insulation, glazing, double-skin facade, etc., are a few technologies used to refine the building envelope and indoor conditions to suit the location.
2. Energy Efficiency Measures in NZEB Design
Energy efficiency measures are implemented by selecting the right-size systems for the building. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 90.1 provides the safety factors in the design and details to conduct simulation to model the design and predict the optimized energy requirements.
Some of the energy efficiency measures used to optimize the HVAC loads are by using:
- High-efficiency chillers
- Underfloor air distribution system
- Passive cooling
- Combined heating and power (CHP)
- Natural Ventilation
- Applying thermal storage using phase-change materials (PCMs)
Once the system is planned and designed, the next crucial step is commissioning these energy-management systems. The commissioning phase must ensure that these systems are installed, calibrated, and performed according to the owner’s requirements.
This commissioning phase must include an HVAC system and controls, any renewable system like solar and wind, light and daylighting controls, etc. Successful implementation of these systems can improve energy efficiency by 5 to 10%.
3. Renewable Energy Measures in NZEB Design
NZEB's design objective is to produce energy consumed by the building through renewable sources. The first two measures, high-performance building envelope, and efficient technology help consume less energy. Renewable energy measures are more expensive than the other measures. Hence, the designers must start with the first two measures and optimize the level of energy consumption to produce renewable energy.
The various renewable energy resources are solar, wind, biomass, and geothermal systems.
A net-zero energy building (NZEB) can be defined as a building that produces as much energy as it consumes when measured at the site.
The three main principles followed by designers to achieve a good net-zero energy building design are:
1. Building envelope measures
2. Energy efficiency measures
3. Renewable energy measures
The various renewable energy resources employed for NZEB construction are solar, wind, biomass, and geothermal systems.