Most existing office buildings are equipped with indoor environmental quality (IEQ) sensors that are connected to the Building Management System (BMS) and provide feedback to the heating, ventilation and air-conditioning (HVAC). Unfortunately, they are often installed in locations selected based on practical reasons rather than for reliable representation of IEQ at actual workplaces. This leads to a difference in the IEQ sensed by the BMS and the occupants, resulting in increased complaints and decreased occupant satisfaction. This paper investigated whether additional sensors spatially distributed in mechanically ventilated office spaces provided a better representation of IEQ than originally installed BMS-connected sensors providing single sensor measurements. Two mechanically ventilated office spaces were equipped and monitored with additional sensors from January to May 2019. Indoor temperature and CO2-concentration were measured with sensors located at the perimeter and the interior of the office spaces. Statistical analysis (confidence intervals and p-value) was used to determine whether the difference in sensor measurements between the two locations was significant. The results showed that the temperature measured at the perimeter was significantly lower (1-1.7 degrees C) than the temperature measured at the interior of the office space. Overall, the difference in the measured CO2-concentration at the monitored locations was statistically insignificant (< 162 ppm). The results suggest that whereas one CO2 sensor seems sufficient to adequately represent IEQ at the office spaces, at least two temperature sensors should be deployed in 20 - 210 m(2) office spaces with mixing ventilation and a 0.33 window-to-wall ratio. Additional analysis showed that accounting for the actual IEQ at the office spaces can be associated with increased energy demand. Using the sensor measurements at the perimeter for HVAC control can increase heating energy use by 0.4 - 40%, depending on the climate zone and building type.

Occupants can provide valuable feedback on the indoor environmental quality of buildings. Research on occupant voting systems (OVS) has demonstrated that apps or electronic devices can act as viable tools for collecting long-term feedback from occupants. However, previous research has only to a limited extent explored occupants’ interaction with OVS and the impact it might have on the reliability of the collected feedback. The present paper presents three case studies on applying a tangible OVS, denoted TiAQ, to collect feedback on thermal and indoor air quality (IAQ) in office spaces. The main objective of the present study was first to explore occupants’ interaction with TiAQ and their motivation. Second, identifying whether feedback collected with TiAQ could represent occupants’ comfort and discomfort with the thermal environment and IAQ. Thirdly, identifying challenges related to occupants’ interaction with TiAQ that might affect the representativeness of collected feedback. The present study was conducted at three office buildings in up to 7 months and demonstrated that TiAQ was suitable for collecting long-term feedback on occupants’ comfort and discomfort with the thermal environment. On average, one vote was cast per day per occupant. Additionally, in one of the office buildings, 60% of occupants reported to have interacted with TiAQ daily or weekly when, e.g., passing the device going to/from the office spaces. Occupants’ expectations of TiAQ and getting “feedback on feedback” need to be further addressed to identify ways to sustain occupants’ long-term use of the device and reduce “ill-willed” interactions.

Occupancy is a key input variable for sizing heating, ventilation and air-conditioning (HVAC) in buildings. However, HVAC designers typically estimate occupancy data based on assumptions which rarely reflect the actual situation. Consequently, these assumptions might lead to underor oversized HVAC systems that either provide too low or too high peak loads or ventilation airflows than actually required to satisfy indoor environmental quality (IEQ) requirements during building operation. To address these issues, existing studies suggest various methods for collecting and analysing occupancy, however mostly in single office spaces or atan overall building level. The objective of the present study was to evaluate the suitability of using passive-infrared (PIR) sensors mounted below occupants' desks for collecting long-term occupancy data in open-plan and single office spaces. The method was tested in two office buildings for seven months. It determined occupant presence and count with an accuracy of 87.5% compared to manual observations. Furthermore, the study demonstrated that occupancy data could be used to (1) generate occupancy schedules for input in building simulation models, (2) potentially reduce design ventilation airflows for HVAC sizing and (3) evaluate decisions to change the office space layout (e.g. number of desks) for more efficient space-use. (C) 2020 Elsevier B.V. All rights reserved.

Tools leveraging information and communication technologies for collecting occupant feedback on indoor environmental quality in buildings are receiving increasing attention. The obvious application examples of these tools, denoted as occupant voting system (OVS), include data-driven comfort models for control of buildings. Even though their application range is much wider, related literature is somewhat scattered across different building-related research fields. The aim of the present paper was to gather and review previous scientific publications about tools characterised as OVS across various applications, ranging from data-driven comfort models for control of building systems to occupant surveys for in-field research studies, as to characterise identified OVS. The present study applied Thematic Synthesis on fifty publications. This resulted in an explicit definition and framework to characterise OVS based on their application, design and used incentives motivating occupant interaction. The review revealed that OVS was applied to obtain thermal comfort models for temperature control, to support facility managers with building operation and to help occupants share their comfort votes with co-occupants. Moreover, OVS was used by researchers as a tool for collecting long-term in-field survey responses. The review also identified challenges related to occupants' interaction with OVS, occupants’ interpretation of used assessment scales, occurrence of extreme votes, inconsistency in voting pattern and privacy concerns in relation to data collection and presentation of occupant votes.

Heating, Ventilation and Air-Conditioning engineers face high demands from their clients to deliver reliable, optimized solutions that perform acceptably in terms of energy use and provided comfort. However, time and resources are scarce to deliver an optimized solution. To ensure that the solution works under most operation scenarios, the design is typically based on a combination of conservative rules-of-thumb, general guidelines and a large safety factor. The consequences are building service systems designed for operating conditions that never or very rarely occur leading to oversized systems. The objective of this paper was to propose a method for identifying oversized air-handling units with variable speed drives. It was demonstrated on a case study including six air-handling units in an office building. The method was able to determine that the air-handling units were not grossly oversized or undersized by comparing the measured airflow and SFP from the part- and full-load operation to the design airflow and SFP. However, the method should be extended to include additional performance criterion such as indoor climate and thermal efficiency to be able to conclusively confirm the size of the units.

Thermo Active Building Systems (TABS), described as radiant heating or cooling systems with pipes embedded in the building structure, represent a sustainable alternative to replace conventional systems by using source temperatures close to room temperatures. The use of suspended ceiling in office buildings to cover acoustic requirements hinders the use of TABS. To measure the reduction of the heat capacity, several experiments are performed in a room equipped with TABS in the upper deck and mixing ventilation. The heat transfer is measured for different suspended ceiling covering percentages, occupancy scenarios and ventilation rates. The gained results indicate that the heat capacity coefficient of the ceiling surface is reduced by around 30% when the suspended ceiling covering is 70% of the total ceiling area, and 45% when the covering area is up to 87%. The results also demonstrate that the ventilation rate has a high influence on the convective heat capacity. When the ventilation rate is increased from 1.7 h -1 to 2.9 h -1 , the heat transfer coefficient increases up to 16% for the same occupancy and suspended ceiling layout.

The International Building Physics Toolbox (IBPT) is a software library developed originally for heat, air and moisture system analysis in building physics. The toolbox is constructed as a modular structure of standard building elements, using the graphical programming language Simulink. To enable development of the toolbox, a common modelling platform is defined: a set of unique communication signals, material database and documentation protocol. The IBPT is an open source and available on the Internet. Any user can utilize, expand and develop the contents of the toolbox. This paper presents structure and essence of the library. Potential applications of the toolbox are illustrated through examples.

In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model of a building provides a systematic way of estimating efficient building designs. However, using detailed numerical calculations of the components in the building is a time consuming process, which may become prohibitive if the DAE model is to be used for parameter variation or optimization. Unfortunately simplified models of the components do not always provide useful solutions, since they are not always able to reproduce the correct thermal behavior. The space mapping technique transforms a simplified, but computationally inexpensive model, in order to align it with a detailed model or measurements. This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters. The technique significantly reduces the modeling error.

This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.

The international building physics toolbox (IBPT) is a software library specially constructed for HAM system analysis in building physics. The toolbox is constructed as a modular structure of the standard building elements using the graphical programming language Simulink. Two research groups have participated in this project. In order to enable the development of the toolbox, a common modelling platform was defined: a set of unique communication signals, material database and documentation protocol. The IBPT is open source and publicly available on the Internet. Any researcher and student can use, expand, and develop the contents of the toolbox. This paper presents the structure and the backbone of the library. Three examples are given to visualize the possibilities of the toolbox.