Jon ThompsonHead of Product Innovation September 24, 2020
The last blog in our Net Zero Carbon Buildings series looked at where to begin with net zero carbon buildings. We found that good energy data and energy efficiency was the place to start and had some tips for overcoming common data challenges.
This time, we’re moving on to look at how best to analyse that energy data once you’ve got it, and what it can tell you about the buildings you manage. Here’s our roundup of the five key energy analysis techniques we think you should pay most attention to.
This is an obvious one but it’s worth stressing its importance as many people try to skip this step. A building’s energy profile is its daily energy consumption data plotted on a line chart at half-hourly intervals. The energy profile for a typical office building usually looks something like this:
The sharp increases and decreases in consumption represent start up and shut down. These should correlate with the times that the majority of people start and finish using the building, or when building services are scheduled to run from and to.
The flat periods either side of this are the base load or non-operational hours. These should be as flat and as low as possible.
A restaurant, however, should look more like this:
In this profile, there is a greater fluctuation in energy use and more of a ‘double peak’, with a drop in energy use between the lunchtime and evening sittings.
Energy analysts often try to skip this stage of analysis because it can be time-consuming or because their energy data platform doesn’t provide this level of detail. But by missing this stage out, you miss the opportunity to truly understand how a building is really used — not how you think it’s used.
In the past, we’ve seen energy profile analysis help make some surprising discoveries, including a huge cannabis farm that was secretly operating above a bank, and an employee who was sleeping in the office!
Profile analysis is also really useful for engaging your customers — whether they are the owners of the building or the tenants. It’s a very graphical way of presenting energy use across a typical day so it’s easy to understand and relate to.
To learn more about this technique, including what to look out for in profiles and how to tackle profile analysis across a large portfolio of buildings, check out our Beginners’ Guide to Profile Analysis.
Regression analysis is a popular statistical technique, which is used in energy analysis routinely. It can help identify which variables have the most impact on energy use within a building.
This is essential because so many things can affect energy use, from static factors such as a building’s age, size, heating system, lighting type and operating hours, to ever-changing ‘dynamic’ factors such as the weather, footfall and production activity. Regression analysis enables you to identify which of those matter the most, which don’t matter at all, and how these factors impact on each other.
For example, a simple linear regression analysis that plots heating degree days in relation to energy consumption, might look like this:
The model clearly shows a positive correlation between heating degree days and monthly consumption, which is not surprising since changes in weather account for the majority of fluctuations in energy use. By looking at three key metrics on the chart (the intercept, the R2 value and the slope) you can also work out how strong the correlation is, how much energy consumption fluctuates because of this factor, and what the building’s base load is.
For more on these three metrics and using degree days, take a look at this blog: Demystifying Degree Days and How to Use Them to Improve Your Energy Analysis.
Once you have identified which variables have the greatest impact on your energy use, you’re ready to move on to data normalisation. This is the process of finding relevant KPIs for energy use.
Data normalisation is crucial because it allows you to carve up your energy data in ways that enable you to compare like with like. In other words, it allows you to see which assets in your portfolio are performing well and which aren’t, by using a standard measure.
A standard KPI for energy is kilowatt hours per square metre of floor space (kWh/m2) but be careful here — it’s a mistake to use a blanket metric such as this for all your sites. As we’ve said, different sites will have different energy drivers.
For example, say you had a chain of gyms and half of the sites had pools and half did not. If you compared all sites using kWh/m2, it wouldn't be a fair comparison because the gyms with a pool would have a much higher energy intensity. Your results would suggest all the sites with pools are the least efficient, which isn't the case. So a better way of comparing your sites, would be to split them into two groups — gyms with pools and gyms without pools — and then compare sites within those groups. You would use a relevant KPI to do that — perhaps kWh/customer.
So in our view, the trick to effective data normalisation is to:
To read more about identifying your core energy drivers and benchmarking your portfolio, take a look at this blog: 5 Steps Towards More Data-Driven Energy Efficiency.
If you only do one form of energy analysis today, do this. Unnecessary energy use in unoccupied buildings is a common problem yet it’s probably the easiest and cheapest issue to resolve. We’ve consistently found that savings of at least 5-10% are possible, simply by properly managing building services during out of hours.
It’s madness to spend hundreds of thousands of pounds on energy saving technology or renewables when your buildings are leaking energy for 12 or more hours each day. If you’re interested in why energy waste out of hours is so common, check out this blog.
But how do you work out your non-operational waste? It all starts with good solid data analysis of course, ideally using half-hourly consumption data. It takes a bit of time but trust us, it’s worth it, and energy data management platforms like Fabriq will make this process much quicker and easier.
Here’s a quick summary of our four-step process to identifying non-operational waste, but for more detail about each step, check out this blog: A 4 Step Process to Identifying Non-Operational Waste
Step 1 — Find your achievable base load
Step 2 — Estimate your optimum base load
Step 3 — Calculate wasted energy in the context of each base load
Step 4 — Communicate your findings to a decision maker
Hands up, our final energy analysis technique isn’t really a technique; it’s more of a tool. Once you have completed your profile analysis, regression analysis, data normalisation and identified your energy wastage during non-operational hours, you will have a good understanding of what energy your sites should be using and why.
To help you monitor energy use continuously across a large portfolio, it’s a great idea to set up alerts so that you’re notified if consumption goes above or below acceptable thresholds. These alerts enable you to spot and respond to problems early, before any more energy is wasted or before a piece of equipment fails.
Most energy data platforms have this feature and while it’s really useful, it can also be a bit inconvenient — you often need to manually input the thresholds into the system and it can get annoying if you’re receiving alerts through your email inbox. That’s why we’ve recently improved this feature in the Fabriq platform. Our software is now able to calculate and set the thresholds for you, by looking back at previous data patterns. It also has a new screen in the interface which displays all your alerts, so it won’t clutter up your inbox.
Is your organisation making the most of energy analysis techniques such as these? They are a crucial early step on the road to net zero carbon. Proper data analysis can uncover a significant opportunity to improve energy efficiency, often at very little cost. It should always be done first, before rushing into investing large amounts of money in engineering projects.
The Fabriq platform makes it much easier and quicker to analyse your energy data using these techniques and others. Its strengths include:
Unfortunately you've missed our latest webinar, 'Net zero carbon buildings: Is your data good enough?' held on 8 October. Please check back in as a recording will be available very soon.