Questions

Can thermal comfort be quantified?

If we follow ASHRAE 55 and define thermal comfort as a "condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation", thermal comfort appears fundamentally difficult to quantify.
Further reading: Djongyang et al. 2010 : Noël Djongyang, René Tchinda, and Donatien Njomo. Thermal comfort: a review paper. Renewable and sustainable energy reviews, 14(9):2626–2640, 2010.

Tags: thermal comfort

What are the advantages of equation-based modeling for building simulation?

Equation-based modeling allows the individual equations describing component behavior to be combined and modified. With component behavior being described by equations, variables do not need to be inputs or outputs anymore, which makes it possible to model situations of flow reversal in an easier way than with typical component-based models. The flexibility of equation-based modeling has been praised for particular applications such as the modeling of controls in HVAC simulation.
Further reading: Wetter et al. 2014 : Michael Wetter, Wangda Zuo, Thierry S Nouidui, and Xiufeng Pang. Modelica buildings library. Journal of Building Performance Simulation, 7(4):253–270, 2014.

Tags: HVAC, level of detail

Based on which criteria should I choose a simulation tool?

There are quite a few criteria to consider when choosing a simulation tool: Although there may be a strategic aspect to the question, it is important to consider the issues to be addressed by simulation on a case-by-case basis.
Tags: tools

What does it take to become a simulation expert?

Expertise in building performance simulation builds on a bundle of skills, of which familiarity with simulation tools is only one. An understanding of the complex phenomena determining building performance is necessary to start simulating. This includes a good understanding of building physics, with the various paths of heat transfer in buildings, but also of building materials and the technologies commonly installed in buildings. With massive input and output data, the knowledge of systematic methods allowing inputs to be prepared and outputs to be post-processed is useful. We may even go so far as to affirm that the skills needed for a full interpretation of simulation results are nothing less than data science. Last but not least, communication skills are necessary, both to obtain information about the simulated buildings and to communicate results.
Further reading: Soebarto 2005 : Veronica I Soebarto. Teaching an energy simulation program in an architecture school: lessons learned. In Proceedings of the Ninth International IBPSA Conference, 15–18. 2005.

Tags: simulation users

Why is it difficult to measure thermal comfort?

Because the physiological basis of thermal comfort (the human thermoregulatory system) is complex. (In particular, it involves dynamics such that steady-state models are only valid for persons in steady-state conditions). The human body uses a variety of processes in order to compensate for thermally non-neutral environments, of which sweating and shivering are the most visible examples. Because personal, psychological and cultural differences are involved. Because, even when trying to reduce the problem to a heat balance, Conduction, convection, radiation, moisture exchange and metabolism play a role physical variables involved are much more than air temperature: radiant temperature (which can be considered to vary according to the angle), humidity, air velocity, clothing and activity. The geometry of the human body plays a role, and this naturally does not make things easier.
Further reading: Carlucci and Pagliano 2012 : Salvatore Carlucci and Lorenzo Pagliano. A review of indices for the long-term evaluation of the general thermal comfort conditions in buildings. Energy and Buildings, 53:194–205, 2012.
Fiala et al. 1999 : Dusan Fiala, Kevin J Lomas, and Martin Stohrer. A computer model of human thermoregulation for a wide range of environmental conditions: the passive system. Journal of applied physiology, 87(5):1957–1972, 1999.

Tags: thermal comfort

Is night temperature setback useful?

The usefulness of night temperature setback - a temporary reduction in heating setpoint temperature - is often a contentious issue. Because of the reduced heat losses associated with lower room temperatures, temperature setback may logically lead to energy savings. However, the amplitude of these energy savings is highly dependent not only on setback amplitude and duration, but also on the building and its thermal mass. The higher the thermal mass, the lesser the energy savings. A potential drawback of night temperature setback is the increased energy needed to reheat spaces. The resulting morning peaks may be detrimental for some systems. Also, comfort might be compromised if reheating does not start early enough. Conversely, lower temperatures at night may be beneficial for sleep.
Further reading: Tariku et al. 2008 : F Tariku, MK Kumaran, and P Fazio. Thermostat setback effect in whole building performance. In Proceedings of Building Physics Symposium, Leuven, Belgium, 1–5. 2008.
Wang et al. 2015 : Yingying Wang, Yanfeng Liu, Cong Song, and Jiaping Liu. Appropriate indoor operative temperature and bedding micro climate temperature that satisfies the requirements of sleep thermal comfort. Building and Environment, 92:20–29, 2015.

Tags: controls, energy savings

How should I choose weather data for building simulation?

Weather data represent an important prerequisite for BPS, so it is worth taking some time to select the right weather file. Some of the aspects to consider will be:
Further reading: Allegrini et al. 2012 : Jonas Allegrini, Viktor Dorer, and Jan Carmeliet. Influence of the urban microclimate in street canyons on the energy demand for space cooling and heating of buildings. Energy and Buildings, 55:823–832, 2012.

Tags: weather

How can I assess a person's surface area?

The famous DuBois formula relates body area A to body mass m and height l as \( A = 0.2025 m^{0.425} l^{0.725} \)
Further reading: Djongyang et al. 2010 : Noël Djongyang, René Tchinda, and Donatien Njomo. Thermal comfort: a review paper. Renewable and sustainable energy reviews, 14(9):2626–2640, 2010.

Tags: thermal comfort