Many engineers are puzzled by questions such as: how to shift or reduce peak heating demand to obtain a better match with a smart grid or renewable energy system? What is thermally more efficient: a heavy concrete building or a light timber-frame building? How effective is night ventilation in warm periods? This course will provide you with the answers to these and many other questions related to dynamic thermal behavior in buildings. We start with a recap of the various heat transfer phenomena that affect buildings’ thermal behavior. Then you will learn how to combine them in dynamic energy balances of relevant building elements such as windows, façades, floors, indoor walls and ceilings, air, furniture, and even the occupants. You will be guided step by step through the construction of a differential equation network, enabling you to understand how to model thermal energy demand and temperature levels during the construction and use of existing buildings and new and innovative building systems. Secondly, you will learn how to solve the resulting equations by using either finite difference or response factor methods. As a result, you will be able to discover for yourself the effects of different designs, and also understand the basic principles which underlie well-known Building Simulation Tools and HVAC software like Energy+, esp-r, DOE-2, Carrier-HAP or TRNSYS. Thus will help you to maximize your correct use of these tools in the future. Finally, you will apply your knowledge by building your own test-software in the language of your choice (e.g. Matlab, R, Python) and solving several equation networks in order to answer the questions posed above and to thermally optimize rooms in buildings in terms of temperature and energy efficiency, and even to determine the thermal comfort level for occupants accounting for radiant temperatures.