Luke Smith from Build Test Solutions talks about making building performance measurement more commonplace, and how you can’t manage what you don’t measure.
Interview with Luke Smith
Luke Smith trained as an architectural technologist. He is now the Managing Director of Build Test Solutions, making building performance measurement and monitoring more accessible, affordable and mainstream.
Being able to measure anything doesn’t mean you should measure everything
The availability of low-cost sensors means there can be a risk of going too far with measurement. For a building that could stand for 50 or 100 years or more, building fabric performance is fundamental.
Building fabric performance measurement includes the whole building heat loss rate (heat transfer coefficient), airtightness, and U-values of the walls, floors and roofs.
Performance measurement is suitable for new-build and retrofit
Non-invasive measurement techniques can be done at any time and with any occupancy, so they are equally suited to retrofit projects and new-builds.
Checking the performance of new buildings immediately post-completion is ideal, but measurement can also support recommendations for single measures like heat pump installation or relatively modest fabric upgrades.
Measurement is just one of the three ‘M’s
Keep in mind the distinction between modelling, measurement and monitoring – the three ‘M’s.
- Modelling is where you start before building anything. As a lot of it is based on prediction, its outputs will only ever be as good as the inputs.
- Measurement checks the as-built performance of the new-build, or measures the before and after performance of a retrofitted building.
- Monitoring is an ongoing process once the building is occupied.
The three are interlinked. For example, by measuring in situ U-values, you can check that the insulation is doing its intended job. Those measurements can go back into the model and help to calibrate it, so you have a better idea of how the building should perform. The fine-tuned model can then be compared to monitoring data, helping to identify issues and suggest remedies.
Smart HTC energy inputs and outputs
Measuring heat transfer coefficient is a good place to start
Understanding the building’s overall thermal performance won’t tell you specifically where heat is being lost, but it’s a good barometer of how well the fabric retains heat.
Build Test Solutions uses a technique called Smart HTC, based on inputting internal temperature data and the total energy consumption over a three-week period into an algorithm. Smart HTC can be done without disrupting the day-to-day occupancy of the building.
Smart HTC charts
Blower door fans aren’t the only way to measure airtightness
Build Test Solutions uses a technique based on compressed air to measure airtightness. ‘The Pulse’ releases a burst of air and the instrument measures the pressure response – how quickly the background pressure in the building elevates and then recovers back to the original condition. It's a quick and non-invasive way of measuring air leakage rate. And, because it’s at low pressure, it doesn’t exert high push and pull forces on the building fabric.
Pulse air permeability testing
In-situ U-value measurements can help to find specific issues
To understand specifics, in-situ U-value measurement gives the heat loss through individual building fabric components. This is the next step if the whole building heat loss measurement has identified an issue and you’re trying to find exactly what the problem is. Taking several readings across the area of a floor, wall or roof helps to show if it has been constructed consistently.
Ongoing monitoring can be based around energy consumption or air quality
From an energy consumption perspective, you could be looking at total energy consumption at the meter, or at a sub circuit level – lighting or ventilation systems, for example.
In terms of health, the main things to monitor are relative humidity, carbon dioxide levels and ambient temperature. But you can also get more in-depth, especially if family members have respiratory illnesses or you’re keen to protect young children. Air quality aspects like particulates, VOCs, radon and carbon monoxide can all be monitored.
What action will you take based on monitoring data?
The main thing to ask is: how often will you look at data you collect? What action will you take based on it? The novelty of simply having data can wear off.
At the same time, devices that can provide warnings – around carbon dioxide or humidity levels, for example – might provide the impetus for behaviour change.
An example of a basic portable temperature and relative humidity logger
Monitoring sensors can be portable, semi-permanent or hardwired
Broadly, three categories of monitoring technologies are available.
- Portable devices are battery powered or mains powered. They can be placed in a single, central location or you might move it throughout the home and check different rooms over different periods. Combined with an existing smart meter, you could begin to understand both energy consumption and air quality.
- A semi-permanent installation might come from a company offering a monitoring platform. A central hub has multiple nodes connected to it. The sensors collect data across the home, all presented through a single dashboard.
- A permanent system is hardwired and can be hugely complex – think a smart energy management system or home energy management platform, verging on home automation. For example, it might track internal humidity and trigger the ventilation system to boost, or open a window.
Portable devices can be small and unobtrusive. Semi-permanent and permanent sensors can be integrated with the building fabric if they’re planned from the outset.
A hardwired system is thousands of pounds, compared to a couple of hundred pounds for a portable sensor.
Consider the Matter protocol if looking at monitoring platforms
Matter is a universal communications protocol that allows devices to interface together. You could have a Matter-enabled smart thermostat, smart home speaker and EV charger, and they could all talk to one another and present you with information centrally.
Devices can already give you a lot of energy consumption information
The general direction of travel is for smart technology to give us a lot of monitoring information. EV chargers are likely to be smart, with an integrated metering capability. Heat pumps typically give the electricity they've consumed and the heat output they've delivered. Smart light bulbs, and other things like them, will come with a hub to track the energy they’ve consumed. Even without proprietary monitoring equipment it’s possible to get a detailed insight into the energy consumption of the home.
Luke strongly advocates using a smart meter, to get gas and electricity consumption data broken down into 30-minute intervals. Consumer access devices (CADs) let you go further, even getting as granular as 10-second intervals. Shorter intervals can be useful if you’ve got solar panels generating during the day, or an EV discharging at night. It lets you track and understand what’s happening in more detail.
Luke shares a few options for monitoring
Portable monitoring options
These simple standalone devices are either battery powered or plug into the mains.
All of the above environmental condition sensors can be great alongside data from your smart meter, smart EV charger, and PV monitoring system.
Power metering smart plugs would also sit in this category.
Semi-permanent monitoring options
These are typically offering the capability to link numerous sensors through a single central hub or gateway
These are hard wired solutions where the monitoring layer may form part of a wider smart home management platform.
Smart thermostats are also examples of basic hardwired solutions that can also typically provide temperature and relative humidity data – Nest, Hive, Tado, Honeywell, Drayton etc.
Find out more
Podcast interview with Tom Fenton (testing the thermal performance of a house)
Podcast interview with Jonathan Dixon (combining smart home technology with energy efficiency)
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