These requirements are difficult to meet using traditional mixed-flow ventilation, but a personalized ventilation system can satisfy them. The WELL Working Group of Hungary Green Building Council (HuGBC) [1] developed a unique concept that supports individual comfort preferences based on six options in line with the WELL Building Standard. The two most important components of the workstation developed based on the WELL Building Standard features include an adjustable-height desk and fresh air supply to individual users. Optimising the conditions of air supply allows you to reduce fresh air volume and install smaller ventilation equipment while the user gets fresher air more adjustable to individual needs. Fresh air supply to individual users may also significantly reduce the risk of infection from droplet-borne diseases.
1. Introduction
In new construction and deep renovation projects, state-of-the-art doors and windows are installed to make the building airtight minimising heat loss. Providing a healthy and comfortable yet energy-saving ventilation solution, however, is becoming increasingly challenging. In office buildings, work efficiency is affected by the volume and quality of air supply in the occupied zone which means the workstation area in this case.
When ceiling ventilation is applied, satisfaction survey respondents often complain that ventilation air parameters at their workstations are not appropriate. In many cases, a driver’s seat offers a higher level of comfort and control to users than their office workstations where they spend 6 to 8 hours a day. Based on WHO data, poor air quality is responsible for the death of 7 million people, that is, one in eight deaths globally, every year [2]. Outdoor air quality is expected to deteriorate due to the energy crisis also in Hungary where many people replaced gas heating with wood or multi-fuel heating in autumn 2022. With outdoor air pollution being on the rise, incoming air filtering and artificial ventilation become increasingly important. Moreover, based on surveys conducted by the Ministry for Innovation and Technology (ITM), 95% of coronavirus cases were caused by droplet-borne indoor infections, with aerosol transmission playing a minor role [3]. Due to requirements of health and comfort, as well as sustainability and energy conservation, it’s high time that mixed-flow ventilation be replaced with systems supplying fresh air directly to users.
Given the current energy disruption and potential future pandemics, all buildings should be assessed to check whether they are operated as designed. Building control systems should be reassessed every 3 to 5 years. Although technical retro-commissioning may seem to be costly, based on the data of 656 buildings studied in the US, the underlying cost of USD 2.8/m2 was recovered in 1.7 years on average [4]. The reassessment of existing buildings allows not only for the optimisation of old systems but also for the installation of innovative end-points.
2. Solutions for indoor air supply
Traditionally, indoor air is supplied using mixed-flow ventilation and dilution [5]. In this case, air can be both supplied and extracted through the ceiling, the floor or even the side walls. The supplied fresh and “young” air is mixed with polluted air in the room and it is growing “old”. The age of air can be determined in any given building.
The age of air
Another increasingly common solution is displacement ventilation [6]. Displacement ventilation works based on the principle of displacement which means that fresh and cool air is supplied at the floor level with pollutants heated up and forced to the ceiling where they are extracted from the room.
The next potential solution is personalized ventilation discussed in this issue also by the article taken over from REHVA Journal 2022/2 [7]. Personalized ventilation has been a long-standing subject of research well illustrated by the schematic drawing on Figure 4 and the image on Figure 5. The solution maintains average ventilation in a given room, while providing the occupants of the room, that is office workers, with personalised ventilation in line with their individual needs.
Personalized ventilation is still subject to research as discussed by the REHVA Guidebook to be published soon. It was also the subject of a PhD thesis at Aalto University in 2021 [8].
Different air supply solutions can be described based on the effectiveness of ventilation [9]. If contaminant sources are known and constant, design aims to remove these contaminant sources at the point of contamination. In this case, contaminant removal effectiveness (CRE) is calculated.
In any other case, the goal is to change air as fast as possible. In these cases, air change efficiency (ACE) is calculated.
A study on personalized ventilation concluded [8] that in this case, air change efficiency is twice as high as with traditional ventilation and it is less dependent on internal heat load (40, 80, 120 W/m2 of floor space).
Air change efficiency [8]
DCV – traditional ceiling ventilation
LVRP – personalized ventilation combined with radiated heating
The commercial launch of workstations providing personalized ventilation will take place soon. They are expected to be widely adopted in the market.
3. Ventilation based on the WELL Building Standard
The WELL building certification system was described in general in the 2021/6 issue of the journal Magyar Épületgépészet. This article discusses only its ventilation aspects in detail [10]. The most important topic covered by the WELL Building Standard is buildings’ fresh air supply. In light of that, WELL makes ventilation in compliance with the standard (MSZ) EN 16798-1 a mandatory requirement and checks compliance with WELL air quality limits conducting on-site testing [11]. On-site measurements are governed by a separate guideline titled the WELL Performance Verification Guidebook [12]. In addition to ensuring basic air quality, WELL offers several strategies to improve indoor air quality (e.g., phased entry, increased fresh air supply, smell source separation, UV sanitization and regular maintenance). An optional optimization strategy in the v2 version of the Standard is enhanced ventilation design [13].
4. Enhanced ventilation based on WELL
The WELL Building Standard v2 provides six options for enhanced ventilation design:
- Fresh air supply exceeding mandatory ventilation by 30% or even 60%.
- Demand-controlled ventilation (DCV). Here the lower requirement is to keep CO2 levels below the limit of 900 ppm or outdoor CO2 level +500 ppm. A facility meets the more stringent requirement if its CO2 level is below the limit of 750 ppm or outdoor CO2 level +350 ppm.
- The requirements of the third solution are the same as the limits in 3.2, but these levels are ensured implementing an engineered natural ventilation system.
- High air quality can also be maintained by continuous onsite ventilation monitoring. In this case, the CO2 limits to be met in the rooms of the facility (other than rarely used areas, such as storage rooms) are 750 ppm or outdoor CO2 level +350 ppm.
- Displacement ventilation system in compliance with REHVA Guidebook No. 01 [6] providing improved ventilation effectiveness compared to mixed-flow ventilation and better air quality in the occupied zone.
- Personalized ventilation system. According to WELL requirements, personalized ventilation should be provided to at least 50% of workstations. To prevent draught, air velocity cannot be higher than 0.25 m/s at the occupant’s head level. Return air diffusers should be located at least 2.8 meters above the floor [13].
5. Personalized ventilation using WELL to develop healthy workstations with personalized ventilation
Personalized ventilation, the last of the above options for monitoring and improving air quality, can work effectively if the user’s workstation is installed in a way that it can connect to the fresh air supply network as designed. Since such products are not yet included even in the offering of Hungary’s premium office furniture vendors, HuGBC’s WELL Working Group decided to create a prototype workstation to demonstrate this ventilation concept. The baseline product is a desk supporting the circulation and filtering of indoor air and fitted with air inlets located at the two distant corners of desk, right above the desktop. (See Figure 8, Ahrend Balance Comfort).
Since this desk has an air filter, a short air duct and inlets already, we believe it serves as a good starting point to connect to the building’s fresh air supply duct with some added innovation. Air can be supplied through the raised floor, or if this is not available, also through the suspended ceiling. In the latter case, vertical air pipes can also be integrated into the furniture.
The concept can be further elaborated in several directions, e.g., by improving the air inlets above the desk, optimising the position or creating an air supply option under the desktop. Users are expected to prefer the solutions that offer them several options to choose from.
The benefits of ventilation solutions supplying air directly to users are currently being researched by several scientists [7]. Of the solutions studied, personalized ventilation was found to most effectively reduce the risk of airborne infections. The risk of infections with general, mixed-flow ventilation and diffuse ceiling ventilation is about 6 and 14 times higher, respectively [7].
6. The persionalized workstation and sustainability
We believe that the proposed solution is suitable to increase the efficiency of fresh air supply and thereby reduce the volume of moved and conditioned air in order to save energy. We think that the energy efficiency enhancements required in the upcoming period should be achieved while also maintaining or improving comfort levels. This can enable the implementation of new and innovative solutions. Using cars as an example, it may be necessary to rethink not only vehicles, but also the road network and modes of transport to find the best solution. That is, for a desk providing personalized ventilation, the installation of a raised floor (pressurized raised floor), the related air duct network, the installation of an air handling unit (fan positioning) and air cleaning technologies (e.g., activated carbon filtering, UV sanitisation and fine particle filtering) should also be considered.
7. Wellbeing at the workstation
This article gives an overview of personalized ventilation solutions for WELL workstations. Workplace ergonomics is also an important part of the concept including an adjustable-height desk, a standing chair and a carpet. A sitting-standing desk is mandatory for 25% of workstations at WELL Standard compliant workplaces, and optimisation points can be granted under the Movement concept of the Standard if the ratio of sitting-standing desks reaches 50% or 90%. Users’ individual lighting needs are supported by a desk lamp capable of doubling typical illumination levels. A small smart green wall installed behind the user is also part of the concept. Besides playing a role in cleaning and humidifying the air, it can also be used to divide large spaces and create individual ventilation zones combined with personalized air supply and appropriately positioned extraction. Importantly, the green wall connects occupants spending 90% of their time indoors to nature. According to the concept, factors contributing to users’ mental health include not only increased fresh air supply and green walls, but also exercises conducive to mental health available at the demo station using a QR code. For more information about the personalized workstation demonstrating various WELL features and the showrooms where the concept prototype was visible, please visit the HuGBC’s WELL website or contact a HuGBC WELL Working Group member.
Summary
Future building ventilation systems will need to be both energy efficient and ergonomic and they should be based on a design minimising the risk of indoor airborne diseases. The presented workstation aims to achieve these goals and offers an innovative solution for which the fundamentals of ventilation systems need to be reconsidered. Personalized ventilation systems supply fresh air to the place where most of it is used, that is, the space occupied by people. Using this solution, users can breathe fresh air and control the way of air supply in line with their individual needs. This article is mostly about office workstations, but the concept can be adapted to many other functions including healthy classroom ventilation which is part of our social responsibility.
Authors:
- Regina Kurucz, MSc Architect, Building Energy Engineer, WELL AP & Faculty, REWELL Consulting Kft.
- Zoltán Magyar, MSc Building Services Engineer, Comfort Consulting Kft.
The authors are members of the WELL Working Group of the Hungary Green Building Council (HuGBC). The Working Group was established in 2019 with the mission to encourage the development of certified and healthy buildings in Hungary. By sharing experience, launching WELL-themed programs, webinars, training courses and making professional recommendations, the WELL Working Group helps stakeholders get closer to a healthier built environment.
Literature
[2] https://www.who.int/news/item/25-03-2014-7-million-premature-deaths-annually-linked-to-air-pollution
[3] Corporate White Paper – Practical guidelines for the development and implementation of a corporate pandemic plan, prepared by the Epidemiologic Modelling and Epidemiology Project of the Ministry for Innovation and Technology
https://vali.ifka.hu/medias/919/20200901_vallalati_feher_konyv_kieg.pdf
[4] https://covid19commission.org/safe-work-travel
[5] Müller, D. at all: Mixing ventilation, REHVA Guidebook No 19, Brussels, 2013
[6] Skistad, H. at all: Displacement ventilation in non-industrial premises, REHVA Guidebook No 1, Brussels, 2004
[7] Melikov, A. at all: Occupant targeted ventilation brings clean air to occupants, REHVA Journal 2022/2, pp. 30-35, https://www.rehva.eu/rehva-journal/chapter/occupant-targeted-ventilation-brings-clean-air-to-occupants
[8] Zhao Weixin: Indoor climate with personalized and centralized room systems, Doctoral Dissertations 55/2021, Aalto University, Helsinki, 2021
[9] Mundt, E. at all: Ventilation effectiveness, REHVA Guidebook No 2, Brussels 2004
[10] Emese Kovács, Nelli Tóth: WELL Building Certification System, Magyar Épületgépészet, Issue 2021/6, pp. 7-13
[11] https://www.wellcertified.com/
[12] https://resources.wellcertified.com/tools/performance-verification-guidebook/
