Net Zero Buildings: A Crash Course
A hot topic in the green energy space is “Zero Energy Buildings”. This is also referred to as “Net Zero Buildings”, “Net Zero Energy Buildings (NZEB)”, “Zero Energy”, and/or “Net Zero”. While there are many names for it - we will just call them Net Zero Buildings - this is a rapidly growing need/industry in the US.
What has caused this need? According to the Renewable Energy Book, published by the US Department of Energy, buildings are the primary energy consumer in the US. So as the country focuses on reducing the impact to the environment and reducing energy consumption, the need for energy efficiency has increased.
The Net Zero Building is a building that produces as much energy as it uses over the course of a year. Advances in building materials, HVAC systems, LED lighting, and renewable energy systems have moved the Net Zero Building from concept to reality.
Defining Net Zero Building
The Depart of Energy (DoE) in coordination with the National Institute of Building Sciences (NIBS) created A Common Definition for Zero Energy Buildings. The National Renewable Energy Laboratory (NREL) published Zero Energy Buildings: A Critical Look at the Definition which has a looser set of definitions and encourages designers, building operators, and property owners to select a definition and performance metrics that will best help their projects/buildings.
As you can imagine, as Net Zero Buildings become more advance and become a marketing tool to help increase property values, you may receive a different definition based on who you speak to.
So for right now, let’s just use DoE’s definition:
An energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy
We will note, that while Zero Energy Buildings are a goal, most if not all buildings will stay connected to the electric grid just in case the on-site energy generated does not meet the needs of the building.
Getting to Net Zero
The first step in reaching Net Zero Building status is to ensure energy efficiency. All efforts must be made to minimize the energy consumed by the building.
This means building with energy efficient materials, ensuring that the building automation system (BAS) is tuned and working properly, reducing demand-side loads, effective maintenance of the building, and improving tenant energy consumption habits.
Building operators and owners should take heed and implement these energy efficiency measures because they are the most cost-effective, have high return on investments, and will reduce the needed on-site renewable energy generation.
Renewable Energy - On-site and Off-site
After ensuring that your building is as efficient as possible, you can focus on renewable energy sources.
On-site energy refers to the generation of electricity on the grounds of the building. Common sources are photovoltaics (PV), wind turbines, hydro electronics, geothermal, and/or biomass. When evaluating what renewable source to choose, consideration should be given to:
How readily available is the energy source?
Is the renewable energy source replicable?
How cost effective is this energy source?
What are the maintenance costs for the system(s)?
Depending on how a Zero Energy Building is defined, renewable energy that is produced off-site or off-campus are acceptable. You will see this application in areas where space is very limited; such as a major city.
If off-site energy is permitted, a renewable energy facility is created at a different location. The energy produced at these sites will create renewable energy credits (RECs). The RECs can be used or sold. Basically, the RECs are used to offset the energy that is consumed by the building. Applying enough RECs can make your building a Net Zero Building.
Net Zero Buildings will soon become the norm in the US. In fact, there are several Net Zero Building projects underway here in Washington, DC. Just remember, before you go out and put solar panels on your roof, you should ensure that you are efficient as possible with your energy.
Interested in making your building a Net Zero Building? The Impact Energy team consists of Certified Energy Managers, Certified Energy Auditors, Commissioning Professionals and Professional Engineers that can help you reach your energy goals.