Objective and approach
The first three subtasks of the Annex 68 focused on particular aspects related to designing and operating energy efficient buildings while ensuring high IAQ – evaluation metrics, indoor air pollution data or modelling approaches. The objective of Subtask 4 was to set the individual “puzzle pieces” into context. To gather the results and approaches of the other subtasks and present them in the context of existing knowledge. This subtask originally aimed to devise optimal and practically applicable design and control strategies. However, as the project progressed, it became clear, that it was impossible as well as impractical to come up with a specific set of “recommended strategies”. It seemed more appropriate to present the whole variety of different approaches that exists in the practice of all project participants involved in the subtask. It was decided to keep the focus on energy efficient and comfortable mechanical ventilation in airtight, low-energy residences.
Transition from theory to practice
The theory for how to obtain a high IAQ is in principle clear and straightforward. There exist international standards, national standards and building codes as well as many brochures, guidebooks and thematic web pages. However, what is the transition of all this knowledge into practice? How do these theories project into the daily life of architects and engineers? This transition, illustrated in Figure 1, was addressed by performing a literature review and a series of interviews among key stakeholders. The results, helped to describe the structure of requirements posed on residential ventilation systems across the different European countries. The stakeholder survey helped to identify implementation barriers and operational challenges related to mechanical ventilation. Despite the fact that the survey included 44 interviews from six European countries, it cannot be considered representative for the whole of Europe. The results indicate that there exists a knowledge gap between “written knowledge” and how things actually work in practice. This can be related to the design, installation, commissioning and operation of ventilation systems.
Figure 1 2: Intended transition from requirements to practice.
Overcoming knowledge gaps can be difficult. There exist certain work routines in the daily life of ventilation designers. National standards and requirements are interpreted in a certain way; the future building owner usually does not have special requirements regarding ventilation systems. Commissioning and maintenance in residential applications are often influenced by tight budgets. In the case of commercial buildings, voluntary certification schemes help to involve the building owner. It is the building owner who usually comes with wishes to fulfil a particular certification level. It adds prestige and helps to acquire future tenants. The same model is rarely applicable in residential projects. Here, a good example in the form of a case study, which clearly describes obtained benefits, can help to escape from established routines.
Inspiration for design and operation
The final report of the Subtask 4 represents our attempt to provide aforementioned collection of good examples. Thus addressing the first main objective of the whole Annex 68 by providing a broad overview of case studies that all represent innovative approaches to design, control and operation of energy efficient indoor air quality management. The report also demonstrates approaches based on sensor technology as well as approaches applying modelling to determine optimal performance. With respect to integration of knowledge from remaining subtasks, the report demonstrates usability of the IAQ metrics developed in Subtask 1 as well as introduces the coupled heat, air, moisture and pollutant modelling.
A case study, in the context of the report, should not be understood only as a description of a finished project (i.e. a building or a system that has been built and evaluated). A case study is simply an integrated piece of information relating to a research study, building project or methodological approach that can provide an innovative insight for the reader.
Each case study is presented using a fixed structure comprising:
Objectives, description and methods – briefly presents the background, aim and main methodology used in the case.
Main results and findings – this section documents how the objectives were fulfilled.
Conclusions and lessons learned – represents a direct connection between the case study and practice. It addresses issues that practitioners can directly transfer into their daily practices, if they find the case study relevant.
Further reading – this section is actually a simplified reference section. Despite the fact that each case study has its own reference section presenting cited literature, the Further reading section presents one, most important source for further reading that provides additional information regarding the case study.
It is not the intention that this report should be read from the beginning until the end. The authors expect rather selective reading based on the immediate interests of the reader. Designers who consider a sensitivity analysis related to internal loads in multifamily houses will seek a different case study than a contractor trying to find space for ventilation in renovated apartments. The authors hope to give inspiration, show direction or even encourage readers to get in contact with the authors to find new ways to provide better IAQ in modern, low-energy residences.
Target audience
The target audience is every stakeholder involved in enabling better IAQ in new and renovated residences. This especially includes architects, ventilation designers, facility managers, property developers and employees of public authorities.
A summary of the Subtask 4 accomplishments
- Subtask 4 conducted a stakeholder survey focused on barriers, challenges and other practical aspects related to installation of energy efficient ventilation in residences in countries participating in the Annex 68. Altogether 44 designers, facility managers, developers, representatives of authorities as well as producers of ventilation systems in 7 countries were interviewed.
- Subtask 4 analyzed written guidance (printed & online guidelines, online tools, brochures, etc.) available for practitioners dealing with energy efficient residential ventilation systems in the Annex 68 countries.
- Subtask 4 reviewed national building codes as well as national and international standards related to design of residential ventilation.
- Subtask 4 published the findings related to above mentioned points in a peer reviewed scientific journal – International Journal of Ventilation
- Subtask 4 published a final report summarizing 24 case studies related to Indoor Air Quality Design and Control in Low-Energy Residential Buildings. The report targets practitioners involved in enabling better IAQ in new and renovated residences. This especially includes architects and ventilation designers, facility managers, property developers and employees of public authorities. The case studies are organized into two large sections: 1. Ways to design residential ventilation in the future; 2. Towards better performance and user satisfaction. The descriptions of case studies are accompanied by “lessons learned” section aiming directly at practical utilization of results as well as recommended future reading section providing most important references.
- Subtask 4 together with Subtask 5 co-organized AIVC webinar focused on Using Metal Oxide Semiconductor (MOS) sensors to measure Volatile Organic Compounds (VOC) for ventilation control. The webinar was held on 4.9.2018 and is available online via the AIVC homepage.
Unresolved technical issues
This subtask will apply the results of previous subtasks (Indoor Air Quality metrics, pollution/emission models and databases developed in the Subtasks 1, 2 & 3 and experiences from the field studies ST5) together with existing knowledge to devise optimal and practically applicable design and control strategies for high IAQ in residential buildings. The strategies will take into account requirements for IAQ based on current standards as well as newly developed metrics based on health effects. Moreover, the type of ventilation systems (decentralized ventilation, active overflow systems etc.) and air supply mode (e.g. intermittent vs. continuous ventilation) will be considered with respect to different building types. Optimal strategy is understood as one that takes into account building energy performance, user comfort and health conditions. A matrix of different strategies shall be created to evaluate possibilities for win-win solutions (excellent IAQ at low energy consumption) as well as other alternatives that will ensure high IAQ.
Use of models and databases developed within the Annex will enable addressing new paradigms for multi-scale and local thermal and air quality management, including demand controlled ventilation that considers the transport of chemical compounds to and from the indoor atmosphere. The subtask will take into account recent advances in sensor technology to identify ways to optimize IAQ without penalising energy efficiency.
On the energy account, the subtask should seek to establish correlation factors between on one side pollutant loads in buildings and methods to mitigate these loads, and on the other side energy consumption. The ambition is that such correlations will be possible to use in future standards and by legislators when specifying regulations for IAQ requirements in highly energy efficient buildings.
Recommendations for follow-up work
The following recommendations for future work rely upon the results obtained in Subtask 4.
Common performance assessment method
It is obvious that a broad range of strategies addressing high indoor air quality in low energy residences exists in practice. However, an approach enabling standardized assessment of these strategies seems to be missing. Since the AIVC introduced a definition of Smart Ventilation, which includes demand controlled systems and favors performance based definition of IAQ requirements, several assessment methods had been developed by particular countries. Integration of knowledge from Subtask 1 and Subtask 4 could lead to development of more generic assessment method that can be used on international level.
Continuous monitoring of performance
Ensuring correct installation and operation through the systems lifetime was one of the aspects mentioned by international stakeholders interviewed during our survey. Further work should be focused on technical systems as well as installation and commissioning procedures that dramatically decrease risk of malfunction in ventilation systems. In current practice, malfunctions are often hidden for many operating hours because the occupants do not have any possibility to assess the performance of their systems. The faults are often discovered when larger damages happen, energy bills “fly up” or when comfort or health of occupants is aggravated. This destroys reputation of modern ventilation solutions. Installers, facility managers and occupants deserve methods and tools that ensure appropriate operation.
Aforementioned recommendations are addressed in the currently prepared IEA EBC Annex 86 - Energy Efficient IAQ Management in Residential Buildings.
Publications and project outcomes
IEA EBC ANNEX 68, Subtask 4: Current challenges, selected case studies and innovative solutions covering indoor air quality, ventilation design and control in residences, Final report, link and exact reference to be added
AIVC Webinar “Using Metal Oxide Semiconductor (MOS) sensors to measure Volatile Organic Compounds (VOC) for ventilation control” https://www.aivc.org/resource/using-metal-oxide-semiconductor-mos-sensors-measure-volatile-organic-compounds-voc
Kolarik, J., Lyng, N. L., Laverge, J. 2020 Metal Oxide Semiconductor sensors to measure Volatile Organic Compounds for ventilation control. Report from the AIVC Webinar: "Using Metal Oxide Semiconductor (MOS) sensors to measure Volatile Organic Compounds (VOC) for ventilation control", held on September 4, 2018. https://www.aivc.org/resource/metal-oxide-semiconductor-sensors-measure-volatile-organic-compounds-ventilation-control
Zukowska, D, Rojas, G, Burman, E, Guyot, G, Bocanegra-Yanez, MDC, Laverge, J, Cao, G & Kolarik, J 2020, 'Ventilation in low energy residences – a survey on code requirements, implementation barriers and operational challenges from seven European countries', International Journal of Ventilation. https://doi.org/10.1080/14733315.2020.1732056
Rode, C, Abadie, M, Qin, M, Grunewald, J, Kolarik, J & Laverge, J 2019, 'Key findings of IEA EBC Annex 68 - Indoor Air Quality Design and Control in Low Energy Residential Buildings', I O P Conference Series: Materials Science and Engineering, vol. 609, no. 3, 032057. https://doi.org/10.1088/1757-899X/609/3/032057