B.W. Olesen

• PhD, Professor
• Technical University of Denmark

Thermally active building systems (TABS) show significant benefits such as providing peak load shifting, peak load reductions, and energy savings. Phase change material (PCM) applications with water circulation have benefits similar to TABS, but PCMs can store more heat per unit volume than concrete due to the latent heat exchange. Radiant panels w...

Personalized Environmental Control Systems (PECS) have advantages of controlling the localized environment at occupants’ workstation by their preference instead of conditioning an entire room. A new IEA EBC Annex (Annex 87 - Energy and Indoor Environmental Quality Performance of Personalised Environmental Control Systems) has recently started to es...

Personalized Environmental Control Systems (PECS) condition the immediate surroundings of occupants, and they are expected to provide increased comfort, health, and productivity. Studies have reported on their benefits and limitations in addressing individual Indoor Environmental Quality (IEQ) factors, especially in terms of thermal comfort and ind...

A Personalized Environmental Control System (PECS) aims to condition the immediate surrounding of occupants. This approach is fundamentally different from typical HVAC systems, which aim to create uniform indoor environments, regardless of the occupant preferences. PECS has several advantages including allowing occupants to adjust their immediate s...

Energy use in building for heating depends on the thermal comfort requirements of the occupants. Personal thermal comfort and clothing behaviours in buildings during winter were studied. The Chinese Thermal Comfort Database contains 41977 sets of data which are from five climatic zones: Severe cold, Cold, Hot Summer and Cold Winter, Hot Summer and...

Published in REHVA Journal Radiant cooling is a promising option for providing thermal comfort with low energy use. The cooling capacity of radiant ceiling panels measured according to standards do not directly represent the cooling provided to the room. An improved measurement method was proposed to improve the prediction of their cooling performa...

Radiant heating and cooling systems have been proven to be an energy-efficient and resource-effective heating and cooling solution for buildings. One of the key features of radiant systems is the possibility of activating and controlling the thermal mass. This feature allows spreading the heat removal from indoor spaces over a longer period, compar...

Personalized Environmental Control Systems (PECS) condition the immediate surrounding of occupants in contrast to conventional HVAC systems. PECS have several advantages including allowing occupants to adjust their immediate surroundings according to their preferences, which could improve their satisfaction with the indoor environment, which may le...

Based on the field measurements and questionnaires surveys carried out in 22 offices in Harbin, China, the group differences (gender, age, BMI, level of education, location groups) in human comfort for different levels of environmental parameters were investigated. It was found that males, elder subjects (above 25 years old) and the subjects with h...

Personal comfort models could be used for the development of automatic controls for personal environmental comfort systems (PECS). These models often use indoor environment and physiological indicators as attributes for estimating the subjective response of occupants. Traditional indoor thermal environment research and standardization recommend 7-p...

Visual comfort plays a central role in building occupants’ comfort, well-being and productivity. It is therefore fundamental to meet the occupants’ visual and lighting needs, carefully accounting for the room layout, usage and activities. In this framework, physiotherapy centres constitute a peculiar case since they are occupied by therapists and p...

IEA EBC Annex 80 - Dynamic simulation guideline for the performance testing of resilient cooling strategies

The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous i...

International thermal comfort standards are applicable for the design and operation of either mechanically cooled or naturally cooled buildings and limited guidance is given for mixed-mode buildings. In this study, a control framework for mixed-mode buildings was defined based on the adaptive comfort model and PMV-PPD method. The proposed framework...

Abstract It is possible to use gas-phase air cleaning to improve the indoor air quality and reduce the energy use for ventilation. However, the energy implications of gas-phase air cleaners and the impact on the air quality are not yet quantified. Therefore, by using a dynamic building simulation, the impact of different clean air delivery rates on...

Abstract No clear guidelines are available for operating mechanical ventilation systems with bypass control in order to maintain the indoor environmental quality (IEQ) levels recommended by standards with the minimum possible energy use. This paper used dynamic computer simulations to study the energy and IEQ implications of multiple mechanical ven...

Phase change materials (PCM) can increase a building’s thermal mass, reducing temperature fluctuations and peaks. However, without active discharge, the PCM’s heat removal capability depends on outdoor temperature fluctuations. The present experimental study investigated the operation and performance of a novel macro-encapsulated PCM panel (MEP) wi...

In many building regulations, the indoor air quality criteria is specified as an absolute level of CO2 concentration, being also the most common parameter used by demand controlled ventilation systems. The use is however challenged by new research showing that the CO2 as a source itself may influence cognitive performance of people. In the indoor e...

In this study, a comparison of nine wireless and two conventional wired temperature sensors (all available on the market) was conducted in a climate chamber with a two-person office setup. Measurements were conducted under both radiant and all-air cooling systems, each with two levels of cooling load (33 and 61 W/m2). Sensors were placed in a total...

Thermostats control the heating, ventilation and air-conditioning (HVAC) system of a building based on the temperature they measure. Integration with communication network technologies allows wireless sensors to be used as the temperature sensing component of an HVAC system, increasing the flexibility in the selection and positioning of sensors. Th...

The number of wireless, low-cost indoor environment sensors is increasing with the improving measurement technology. These sensors could potentially replace the wired sensors integrated in Building Management Systems or could be used to develop a remote, low-cost commissioning process for buildings (without BMS). This study investigated the effect...

This study assessed metrics available in standards (ISO7730:2006, ASHRAE55:2017, ISO17772:2018, EN16798:2019) and certifications (WELL, BREEAM, LEED, DGNB). A set of measurable IEQ parameters and indicators for short and long-term evaluation were identified. The standards propose certain parameters: operative temperature, CO2 concentration, illumin...

The effect of indoor environment parameters specified in national and international standards on simulated energy use of an educational spaces were assessed. Standards considered included those of EN, ISO, ASHRAE and ISHRAE. Eight different climatic locations were considered. Energy use to maintain IEQ parameters according to the highest category,...

There is an increasing interest in evaluating the indoor environment on a yearly basis. The technical report (TR16798-2) to EN16798-1 recommend criteria for thermal comfort evaluation based on heating and cooling seasons, but do not give clear indications of how to manage the transition between them. This study used dynamic simulations to evaluate...

Quality of the indoor environment has become an important parameter to account for in new and existing buildings due to the increasing number of people spending most of their time indoors. Generally, the design and evaluation of indoor environments in buildings rely on appropriate guidelines and recommendations. National and international IEQ stand...

In most countries, PMV is the reference index for the assessment of thermal comfort conditions in mechanically conditioned environments. It is also the basis to settle input values of the operative temperature for heating and cooling load calculations, sizing of equipment, and energy calculations according to EN 16798-1 and 16798-2 Standards. Over...

The common placement of thermostats in offices might not reflect the actual thermal environment around occupants and influence the energy use. In this research, it is questioned which type of thermostat at which location better represents the conditions in the occupied zone and what is the effect on energy use. To answer this, simulations of indoor...

High temperature cooling systems have several benefits, such as their ability to create a comfortable indoor environment in an energy-efficient way. Among these systems, those with high thermal mass such as Phase Change Materials (PCM) in integrated components and Thermally Active Building Systems (TABS) are of particular interest, but it is widely...

The common placement of thermostats in offices might not reflect the actual thermal environment around occupants and influence the energy use. In this research, it is questioned which type of thermostat at which location better represents the conditions in the occupied zone and what is the effect on energy use. To answer this, simulations of indoor...

The most commonly used thermostat control variable in heating, ventilating and air-conditioning systems is air temperature. The requirement for thermal comfort in international standards are however based on operative temperature. Will the adoption of operative temperature based control lead to better thermal comfort and how will this affect the en...

Heat transfer coefficients are often used to describe the thermal behavior of radiant systems and how it transfers heat between the cooled/heated surface and the room. Inconsistency is evident in the values/expressions suggested in literature and standards. This study investigated possible sources of discrepancy in an extensive literature review of...

Some modern buildings are always designed with large glazing area. Glazing ratio (GR) or window to wall area ratio is an important factor that affects thermal loads. It also has impact on thermal environment because solar radiation through windows and warm/cold window surface temperature in different seasons. In this study, GR of 30% and 100% were...

Mechanical systems (heating, cooling, and ventilation systems) allow actively controlling the indoor environment in buildings. However, buildings can also be naturally conditioned or conditioned in a hybrid way (benefiting from both natural ventilation and mechanical ventilation in different times of the year or day, also known as mixed-mode). Seve...

This study reports the main findings from a series of human subject experiments, where the subjects were exposed to the different indoor environments created by different cooling systems. The studied systems were a radiant cooling system (chilled ceiling and mixing ventilation, CCMV), and a combined radiant and convective cooling system (radiant di...

Heat transfer coefficients are often used to describe the thermal behaviour of radiant systems and how it transfers heat between the cooled/heated surface and the room. In addition to current standards, numerous studies have been conducted to obtain the heat transfer coefficients through experiments and simulations. However, inconsistency is eviden...

The performance of suspended ceiling panels with phase change materials (PCM) for comfort cooling applications in office rooms was studied. The panel consisted of a metal casing, which encapsulates the PCM. Water can circulate through the pipes embedded in the panel to influence the latent energy storage of the material. To evaluate the performance...

Two commercially available ceiling panels, one metal and one gypsum incorporating microencapsulated PCM were compared experimentally to determine their limitations and ability to provide an adequate indoor thermal environment. The experiments took place from February to May 2018 in a climate chamber at the Technical university of Denmark. In total,...

The aim of this study was to determine favorable operation conditions for ceiling panels containing phase change materials (PCM) for cooling applications in office rooms. A recently renovated room in the Technical University of Denmark was used to have realistic boundary conditions. Using TRNSYS 17, the performance of the PCM panels during the cool...

A model of three PV/T collectors of 3.9 m2 area was developed in TRNSYS for analysing its cooling potential in Athens, Greece; Madrid, Spain; Milan, Italy; Bucharest, Romania; Frankfurt, Germany; Copenhagen, Denmark and Oslo, Norway between 1st of May and 30th of September. An in-depth analysis over the model was conducted for Copenhagen, Denmark w...

Heat transfer coefficients are often used to describe the thermal behavior of radiant systems in buildings and how they transfer heat between their cooled/heated surfaces and the room. In addition to current standards, several studies have been conducted to determine such heat transfer coefficients by means of experiments and simulations. Inconsist...

The most commonly used thermostat control variable in heating, ventilating and air-conditioning systems is air temperature. However, people’s thermal comfort responds to operative temperature more directly than air temperature. Will the adoption of operative temperature based control lead to better thermal comfort and how will this affect the energ...

Wireless indoor environment sensors that can measure temperature, relative humidity and CO2 concentration have recently developed to a stage where they can be used in Building Management Systems (BMS) for building control or could be used to develop a remote commissioning process for buildings without BMS. This provides new opportunities for user i...

The number of wireless, indoor environment monitoring devices are increasing with the improving measurement technology. This development enables the possibility of deploying many of these sensors in buildings to improve the indoor environment control. Wireless sensors could possibly replace the wired sensors that are integrated in Building Manageme...

Activating the thermal mass of a building by implementing Thermally Active Building Systems (TABS) assists in reducing energy use for thermal management of buildings by utilizing a low temperature heating and high temperature cooling approach. Coupling TABS with geothermal heat pumps that use low-grade energy source in addition to model-based predi...

This study investigates the heating operation performance of a multiple-source multiple-use heat pump system, consisting of a sky source heat pump, a ground heat exchanger and floor heating heat pump in an experimental facility named RE (Renewable Energy) House. The novelty of this system is that the ground thermal state is maintained by the combin...

Radiant heating and cooling (RHC) systems are increasingly applied due to well-known technical advantages such as increased thermal comfort, space saving, and reduced energy use. The building sector is currently one of the largest consumers of fossil fuels; since there has been much concern on the energy use, many directives and legislations have b...

This study reports the results from an experimental comparison of two cooling systems. The studied systems were a radiant cooling system (radiant ceiling panels and mixing ventilation), and a combined radiant and convective cooling system (combination of a different kind of ceiling panels and diffuse ceiling ventilation). The experiments were condu...

GEOTABS buildings combine an energy efficient heating and cooling system (Thermally Active Building Systems, TABS) with a renewable energy resource (ground, GEO) to heat and cool buildings in an energy efficient and sustainable way. Within the scope of a new EU project (HORIZON 2020-10 project EE-04-2016), hybrid GEOTABS buildings are studied in d...

This study examined the effect on energy use and thermal comfort when combining microencapsulated phase change material (PCM) with radiant ceiling panels in a two-person office. The performance of the system was studied during the cooling season in the climates of Copenhagen, Denmark, and Rome, Italy, using a basic cooling strategy and a night cool...

This study examined the performance of Phase Change Material (PCM) in active ceiling panels under extreme climate conditions. The purpose was to reduce the annual energy use and still maintain an indoor climate corresponding to Category II in the European Standard, EN15251. Dynamic yearly simulations were run with a building simulation software for...

Radiant heating and cooling systems, and Thermally Active Building Systems (TABS) in particular, have several advantages such as benefiting from the low temperature heating and high temperature cooling principle, coupling with renewable energy sources, peak shifting and peak load reductions. When using TABS, most building simulation models assume a...

The aim of this study was to examine the performance of phase change material (PCM) in active ceilings for an office room under different Danish building regulations for both heating and cooling purposes. A model of a two-person office room was simulated with the only heating and cooling source being radiant ceiling panels containing PCM. The targe...

Performance evaluation of radiant and convective cooling/heating systems Survey on HVAC related potential research themes for office buildings

Free-hanging horizontal and vertical sound absorbers are commonly used in buildings for room acoustic control; however, when these sound absorbers are used in combination with Thermally Active Building Systems, they will decrease the cooling performance of Thermally Active Building Systems and this will affect the thermal indoor environment in that...

Given the global trends of rising energy demand and the increasing utilization of low-grade renewable energy, low temperature heating systems can play key roles in improving building energy efficiency while providing a comfortable indoor environment. To meet the need to retrofit existing buildings in Nordic countries for greater energy efficiency,...

PhotoVoltaic/Thermal (PV/T) panels were used for cooling water through the principle of nocturnal radiative cooling. This water was utilised for discharging Phase Change Material (PCM) which was embedded in ceiling panels in a climate chamber. Three different sets of flow rates were examined for the solar and the PCM loops, for five days each. The...

Air-based and water-based indoor terminal units can be used to heat and cool indoor spaces. The choice of terminal unit has direct effects on occupant thermal comfort, and on system performance through energy and exergy inputs to heating and cooling plants and through energy and exergy inputs to auxiliary components (pumps and fans). Energy and exe...

A simulation study was conducted to examine the possibility of using PhotoVoltaic/Thermal (PV/T) panels and unglazed solar collectors for producing cold water through night-time radiative cooling. The cold water was used as the medium for cooling an office in three different cities (Copenhagen, Denmark, Milan, Italy and Athens, Greece) during the c...

The real energy performance of buildings depends both upon deterministic aspects (building's physics and engineering systems) and probabilistic aspects such as weather and occupant behavior. Occupant behavior is usually not directly considered when calculating the expected energy performance of buildings. In fact, field test studies all over the wo...

The possibility of using PhotoVoltaic/Thermal (PV/T) panels for producing cold water through the process of nighttime radiative cooling was examined experimentally. The cold water was used to discharge Phase Change Material (PCM) in ceiling panels in a climatic chamber. Both night-time radiative cooling and night-time ventilation were used as the d...

Thermally-Active Building Systems (TABS) have proven to be an energy-efficient and economical cooling and heating solution for commercial buildings. However, acoustic comfort is often jeopardized in such buildings, due to the thermal requirements of the system. More knowledge is required to understand to which extent a layer of hanging sound absorb...

Recently there has been a considerable increase in the use of Thermally-Active Building Systems (TABS) in Europe as an energy-efficient and economical cooling and heating solution for buildings. However, this widespread solution requires large uncovered hard surfaces indoors, which can lead to a degradation of the room acoustic comfort. Therefore,...

Floor covering resistance (material and thickness) can be influenced by subjective choices (architectural design, interior design, texture, etc.) with significant effects on the performance of a radiant heating and cooling system. To study the effects of floor covering resistance on system performance, a water-based radiant floor heating and coolin...

The thermal environment of buildings with a second "skin" and semi-outdoor space is examined in the present study. A literature review was conducted on similar structures and only a few studies were found focusing on the thermal environment. Two different building case studies were chosen with different building and shield geometry, different level...

The weather dependency of nocturnal radiative cooling technology with solar collectors is investigated in this study. Two types of solar panels are investigated: unglazed collector and photovoltaic/thermal (PV/T). A computational model of both panels, validated by comparison with previous experimental results, enables to realize a parametric study...

The thermal indoor environment and the energy performance of a plus-energy house are evaluated in the present study. The study case is EMBRACE, a two-storey dwelling of 59 m 2 designed to host a single family. The building includes a semi-outdoor space covered by a glazed envelope, where the thermal environment is also investigated. The house is lo...

There are several examples of buildings that are partially or entirely covered by a transparent shield, such that a semi-outdoor space between the building and the shield is created. The purpose of the present study was to investigate the impact of the addition of a shield on the energy use of a building. Two case study buildings were examined; the...

Due to a shortage of energy resources, the focus on indoor environment and energy use in buildings is increasing which sets higher standards for the performance of HVAC systems in buildings. The variety of available heating systems for both residential buildings and office buildings is therefore increasing together with the performance of the syste...

Energy use in buildings accounts for a large part of the energy use globally and as a result of this, international building energy performance directives are becoming stricter. This trend has led to the development of zero-energy and plus-energy buildings. Some of these developments have led to certain issues regarding thermal indoor environments,...

When designing buildings and space conditioning systems, the occupant thermal comfort, health, and productivity are the main criteria to satisfy. However, this should be achieved with the most energy-efficient space conditioning systems (heating, cooling, and ventilation). Control strategy, set-points, and control dead-bands have a direct effect on...

Real energy performances of buildings depend not only on deterministic aspects, such as building physics and HVAC systems, but also on stochastic aspects such as weather and occupants’ behavior. Typically, occupant behavior is not adequately considered when calculating the expected performance. As a result, field test studies all over Europe have s...

Three space heating systems (floor heating with different floor covering resistances, radiator heating with different working temperatures, warm-air heating with and without heat recovery) were compared using a natural gas fired condensing boiler as the heat source. For the floor heating systems, the effects of floor covering resistance on the whol...

The aim of this study was, by using a building simulation software, to prove that a radiant cooling system should not be sized based on the maximum cooling load but at a lower value. For that reason six radiant cooling models were simulated with two control principles using 100%, 70% and 50% of the maximum cooling load. It was concluded that all te...

Nighttime radiative cooling technology has been studied both by means of simulations and experiments, to evaluate its potential and to validate the existing theoretical models used to describe it. Photovoltaic/thermal panels (PV/T) and unglazed solar collectors have been chosen as case studies. An experimental setup has been constructed and tested...

The present study is concerned with the air and operative temperatures at different locations in a detached, one-story, single family, plus-energy house. The house was located in Denmark and it has been used as a full-scale experimental facility with heated dummies to simulate occupants living in the house. The house had gone through a year-round m...

Field studies suggest that the availability of adjustable thermostats, operable windows and other controls has a positive impact on comfort, the incidence of building related symptoms and productivity. This laboratory study was designed to further investigate how having or not having control over the thermal environment affects human responses to t...

The objective of this study was to analyse operative temperature drifts and occupant satisfaction with thermal environment in office buildings utilizing embedded radiant heating/cooling systems. Three office buildings were investigated: Town Hall in Viborg, Denmark (floor area 19400 m 2), IDOM, Madrid, Spain (16000 m 2), TiFS, Padua, Italy (2200 m...

There has been a growing international focus on reducing the energy consumption in buildings. This study evaluates the energy performance and indoor environment of a plus-energy house located in Denmark. The studied house was a detached, single-family house, built for the Solar Decathlon Europe competition in 2012 by the Technical University of Den...

The studied house was a detached, one-story, single family, plus-energy house located in Denmark. The house was being used as a full-scale experimental facility without actual occupants living in the house. The house was operated a whole heating season (October to April, both months included) and different heating strategies were tested during this...

The purpose of this study is to evaluate the energy consumption and indoor environment of a plus-energy house located in Denmark. The house is a detached, single-family house built for the Solar Decathlon Europe competition in 2012 by the Technical University of Denmark. The house is currently being used as a full-scale experimental facility. The m...

Thermal comfort is one of the most important aspects of the Indoor Environmental Quality due to its effects on well-being, people's performance and building energy requirements. Its attainment is not an easy task requiring advanced design and operation of building and HVAC systems, taking into account all parameters involved. Even though thermal co...

The present study investigated different combinations of floor/ceiling heating with mixing/displacement ventilation and their impacts on the indoor air distribution and ventilation effectiveness. Measurements were performed in a room during heating season in December. The results show that indoor vertical air temperature differences and air velocit...