In a previous article we introduced the EU-funded QUANTUM project and its tools to help address the performance gap. Here we highlight the benefits experienced by example projects using the tools and uncover some of the common difficulties projects experience when trying to improve the quality management of building services.
The QUANTUM project brought together three innovative tools new to the market to support various stages in the quality assurance journey, with the ultimate aim of reducing the performance gap between design intentions and use commonly experienced in buildings:
- The Performance Test Bench (PTB) by Synavision, Germany â€“ the first tool for the digital specification and automated validation of Building Management System (BMS) data
- Comfortmeter by Factor4, Belgium â€“ A web-based occupant questionnaire for perceived user comfort to understand in-use building conditions
- Next Generation Power Analyser (NG9) by Energy Team, Italy â€“ a cost effective and easy to install in-situ energy metering device with online data analysis to supplement existing metering where necessary
Quality (in engineering terms) is the degree to which inherent characteristics of an object fulfil its requirements. Here we focus on the Performance Test Bench (PTB) and Comfortmeter surveys as tools to help improve the quality of building services. Use of the NG9 energy meters typically supported data acquisition for the PTB as necessary for some buildings.
Performance Test Bench (PTB)
The purpose of the PTB is to verify that building services are operating in line with the clientâ€™s requirements. The tool automatically checks measured parameters against a series of â€˜rulesâ€™ established with the help of a library of templates for various building systems. During the QUANTUM project the PTB was tested in a variety of buildings and with a number of building services, including air handling units, heating and cooling units, heat pumps, etc. Most of the identified discrepancies involved air handling units.Â However, in one building portfolio it was found that the majority (70%) of air handling units could be tested using a single template from the PTB, showing the potential for ease and efficiency of setup.
The tool was able to identify the following issues with building services, which led to energy and/or cost savings for the buildings or improvements in occupant comfort, satisfaction and productivity:
- Faulty and unsuitably located sensors or meters
- Automated systems permanently operating in manual mode
- Inappropriate schedules for the services
- Incorrect supply air temperature set points
- Heating and cooling operating at the same time
- Pumps continuing to run even when there was no heating or cooling demand
- Night set back mode not operational to give lower system temperatures out of hours
- Potential to reduce fluctuation of the duct pressure in ventilation systems to reduce stress on the system (i.e. improve lifespan of system)
- Potential to reduce heat pumps switching off and on, reducing stress on the heat pump system (i.e. improve lifespan of system)
By identifying these issues it was estimated that a university building in Austria could save EUR 10,000 per year through direct (energy) and indirect costs savings (e.g. lifespan of systems) with a 10% reduction in energy consumption. It was also determined that another building portfolio could benefit from a 16% reduction in energy demand from adjustments made to the operation of the air handling units alone.
Here we show some examples of â€˜rulesâ€™ applied in the PTB and the simplicity of the associated outputs.
The rule being verified in this analysis on a lecture room was that the supply air input from outside should not operate if the occupancy in the space is sufficiently low during normal occupancy hours (indicated by CO2 sensor concentration). However, the chart shows unnecessarily high amounts of outdoor air supply over the period being analysed (red sections of the graph, indicating that the rule was not being met) suggesting the fan control setup was incorrect. This incoming air would be heated, thus addressing this represented a great potential heating energy saving.
Another active rule was simply checking whether the air handling units (AHUs) serving offices was â€˜onâ€™ during the required period of operation. In this case, it was apparent that the AHU was not operational every Tuesday after a certain point. On further investigation, it was identified that the unit control had been reset for Tuesday to operate under a weekend mode of operation due to a public holiday. However, this had not been reset after the event, hence remained non-operational each week until the anomaly was identified using the PTB. While this may not have financial or energy saving benefits it would have comfort implications for occupants.
Comfortmeter occupant surveys
Comfortmeter investigates the performance of a building through its daily users. It covers comfort-related topics through over 55 questions, and documents the performance of the building in respect of thermal, visual and acoustic comfort, indoor air quality, individual control possibilities and the office environment. Surveys carried out at two example offices occupied by the same company (i.e. with the same functional use) demonstrated the differences in perceived occupant comfort and the areas in which to focus to address these issues. One was a modern building specifically designed for the client and the second an older generic office building rented by the client.
These example survey report outputs show how the building performance within each metric compares with average, best, and worst practice benchmarks from the Comfortmeter tool. In the older office (right), there is notable poor satisfaction across all elements but it implies particular inadequacy of the HVAC systems (temperature and air quality metrics) where the building has not specifically been designed to accommodate the occupancy and usage profiles of the users. These outputs and the subsequent further detailed analysis also had potential productivity penalty/benefit assigned to them within the Comfortmeter survey tool and hence can help direct building owners and facilities managers towards the issues with the greatest impact on the occupants and their business.
Difficulties of implementation and lessons to take forward
During the QUANTUM project the tools were implemented on existing buildings, but with consideration of an overall quality process that could be applicable over an entire construction life cycle from initial design through to occupation. This presented some challenges when implementing the PTB in particular. For example:
- For existing buildings, not all required monitoring may be in place to thoroughly evaluate building performance. In such cases new meters or sensors will be needed, which is where the NG9 meters may be useful for retrospective installation.
- In some cases, data required for future verification was measured by the Building Management System (BMS) as part of the system function/control, but it was often not â€˜loggedâ€™ or stored for sufficient time to allow for analysis.
- When the required procedures are not embedded from outset, it can be difficult to arrange appropriate data extraction from a BMS (e.g. format, security issues).
Each of these issues would inevitably lead to increased costs, hence they emphasise the importance of embedding the required approach to technical monitoring and performance verification from the outset of the project to ensure the required data collection and storage is incorporated and data extraction schedules are put in place so a quality approach can be followed.