I am part of a group of architects and engineers that is thinking about a definition for a Real Energy Neutral Building definition. As many of you will know there are many different definitions and adding one to the list might lead to more confusion, so we try to have a holistic approach and find a definition that might incorporate several other definitions as well. This is still in a concept phase, and it is more a philosophical discussion than a technical one. Nevertheless I would appreciate input for what I have written below. Perhaps someone else has already thought of it and it would be a waste to re-invent the wheel.
Of course many will say that energy neutral means that the energy bill at the end of the year is 0, or something similar. But if a building is not used, or only partly used, it does not or not fully serve its purpose whilst the energy consumption can come pretty close to that 0, especially with on-site energy generation. We started to think about how the use of the building can be encouraged more whilst still saying it is (close to) an Energy Neutral Building.
Basically the idea is this: The "Definition" is a standardized method for determining the energy efficiency indicator based on the real energy use of the building. The energy efficiency is not just defined as energy consumption per m2/ft2 but it also incorporates the amount of time the building is actually used. In my opinion an unused building is simply a large and expensive piece of art with no real purpose other than to look pretty (or not, depending on your taste). If we take the amount of hours that a building is used for normal office hours and use that as a baseline (lets say 65 hours/m2 per year) a building with an energy consumption of 1,386,000 kWh and floor area of 12.000 m2 will have an energy use intensity of 115,5 kWh/m2. This would be the traditional EUI. But if we incorporate the use of the building as a correction factor we might see a different picture. Let's say the total number of hours the building is used is 100h/m2/year. The same energy use intensity would be different: 115.5 / (100/65) = 75 kwh/m2/year. In some simulations we have run we could see the total energy consumption going up when buildings were used more intensively, but the "Definition" that we used showed that it dropped or stayed the same.
This may be quite different from the way we are used to measure the EUI, but with this "Definition" the energy is not just used for creating a healthy/comfortable indoor climate but also incorporates how effectively we actually use the building. It also uses the actual data of the building and the way it is used. It is therefor not exactly a simulation methodology, but I think the people on this forum might have some interesting insights and knowledge that might help with understanding this concept.
Just as a reminder, this is still work in progress. Perhaps something like this already exists. Perhaps it is not useful after all. It is simply a question that arose when we were discussing what a Real Energy Neutral Building is. But I believe we will never progress if we do not question the way things are done by default. Perhaps we are already on the right track as it is, perhaps this definition can open a new chapter on our quest to a more energy neutral and sustainable society.
Please share your thoughts and opinions!
