The importance of prioritizing on reducing the GHG emissions from building sector is no recent news. The building sector alone accounts for 40% of the total emissions, and are mostly related to the energy consumption of the buildings. To identify how to reduce the emissions effectively, the first step should be to understand how they are being produced and released. This in turn helps in making better decisions in reducing the GHG emissions. For instance, a building utilizing 100,000 kWh of coal power will have a much higher environmental footprint than a building that uses 100,000 kWh from green sources.
This is where data comes into the picture. If energy efficiency measures are implemented without referring to the data, they may not yield the expected results. Energy efficiency measures aim to reduce the emissions and the operating costs as well. However, depending on the efficiency measures without understanding the building needs will probable lead to only one effect being achieved.
Let’s understanding energy data a little better.
Generating Energy Data with Benchmarking
Benchmarking is an effective method of obtaining a building’s energy consumption data. If you have questions like:
- How much energy does my building use every year?
- What’s the consumption profile breakdown? What sources are being used?
- Can I compare energy consumption of multiple buildings?
Then benchmarking is the answer.
New York City has generated the largest building energy consumption data set in the US, thanks to benchmarking. Local Law 84 of 2009 made benchmarking mandatory for building with area over 25,000 sq. ft. Benchmarking data is referred to calculate the ENERGY STAR scores for indicating the building performance on the scale of 1 to 100. This score is compared to other buildings of its type. To understand this a little better, consider an example:
- A score of 50 means the building outmatches 50% of similar buildings. A score of 90 says that the building is one amongst the top 10%.
In simple words, getting a better ENERGY STAR score is what the building owners should be aiming for.
In NYC, under Local Law 33 energy grades from A to F are assigned to buildings based on their ENERGY STAR scores.
Energy Modeling to Reduce Emissions and Energy Costs
Energy modeling is used to get a better and more accurate picture of how the building uses energy. One of the benefits of energy modeling is that it can be done during the early stage building design i.e. even when the building hasn’t yet been constructed. This gives a precise picture of the return on investment for energy saving and reducing GHG emissions.
The issue with energy upgrades is that they are often calculated and implemented in isolation, with little to none consideration of other building systems and their interaction. This is mitigated in energy modeling since it analyses the entire building. There are several interactions that happen in the building and focusing on one part of it doesn’t always solves the issue and the expected result can vary significantly from the actual result.
For NYC buildings, a considerable cut in emissions will result in avoiding penalties under Local Law 97, which will take effect starting from 2024. Buildings over 25,000 sq. ft. are covered under Local Law 97 and the penalty is $268 per metric ton CO2 equivalent over the limit.
The building’s energy consumption data should always be considered before upgrading to save energy and cut emissions as this becomes an excellent starting point to build on. However, a detailed consumption is necessary to make the optimum investment decisions.
Benchmarking can help keep a track of the energy consumption and also allow comparing with similar buildings. Energy modeling can be useful in analyzing the energy consumption, this can also be done even when the building exists only as design documents.
Michael Tobias, PE, is the principal and founder of New York Engineers. He leads a team of over 50 MEP/FP engineers. Although New York Engineers main headquarters are in NYC and Chicago the business has led over 1,000 engineering projects in New York, New Jersey, Connecticut, Pennsylvania, Florida, Maryland, and California, as well as Malaysia and Singapore. Michael is an advocate for green technology and energy efficiency, and approaches engineering as a vehicle to raise the quality of life