What is SIMPLE?

SIMPLE is a Building Performance Simulation tool developed with the purpose of modernizing Building Performance Simulation. This includes, but it really is not limited to, more appropriately integrating how "people" experience and interact with the buildings they use. There are two main reasons for this.

The first one is that—based on the research that led to the design and development of SIMPLE—Building Performance Simulation tools should be able to, at least (again, there are more requirements) allow us to perform holistic simulations (i.e., integrating heat, moisture, light and acoustics). The reason for this is that, when people get into a room, they just feel it. They do not separate—as Software and Building Scientists do—the Thermal from the Daylight from the Acoustic domains. So, SIMPLE aims to enable holistic Building Performance Simulation.

The second reason to focus on people is more related to the changing challenges of Building Science. One or two decades ago, many of the buildings we lived in were crap not very well insulated, they weren't air-tight, their windows weren't sized to balance solar heat gains, daylight, and insulaton, and so on. Under these conditions, it made a lot of sense to focus just on building physics. We did not really know how to design and build healthy, comfortable and Net-Zero energy buildings... but that has changed. There are many examples of extremely good buildings today and Software has become cheaper, more affordable, fast, and easy to use. Today, we understand and can predict the effects of building physics better than ever before, which means that the main gap in knowledge lies in human factors. Insulating an open door is absurd, so we need to really understand when and why people choose to open doors, so we can plan in advance and design buildings that make their comfort and behaviour compatible with the energy efficiency and health needs we have identified.

I like to think of this as a change of paradigm, where we stop focusing on 'occupants' and finally start focusing on 'humans'. If you want to understand a bit more the difference I make between Occupants and People read this.

Do we need SIMPLE? Can't we just keep using other tools?

I have been working in Building Simulation Tool space for nearly a decade now. During this time, I have tried to combine simulation tools and methods, and also to make simulation more accessible to people. For example, my MSc research focused on the integration of Radiance and EnergyPlus. It was then when I started developing Groundhog, which intended to put Radiance in everyone’s hands. While developing Groundhog I realized that Radiance could use some sort of wrapper to make it a bit friendlier by offering out-of-the-box optimizations and pre- and post-processing. This motivated me to develop Emp, a Radiance orchestrator. Both projects—Radiance and Emp—have already died for various reasons.

During my time developing building performance simulation tools I have learned about an enormous amount of undeniable virtues that currently available tools—e.g., EnergyPlus and Radiance—have: they have been extensively validated, they are open source, they are free (as in freedom), and so on. Unfortunately, I have also seen many drawbacks. For starters, these tools were not really meant to be embedded on other tools. Radiance confesses this quite clearly:

“These routines are designed to aid the programmer who wishes to call Radiance as a library. Unfortunately, the system was not originally intended to be run this way, and there are some awkward limitations to contend with…” (Radiance’s raycalls.c)

Also, these tools were developed decades ago. Radiance was developed before the gaming and animation industry invested millions in improving rendering techniques, and EnergyPlus tends to focus too much on building physics even if we now know that we need to pay more attention to people’s behaviour in buildings (because insulating an open door is pointless). Also, programming was different back then, with different source control systems and way less people who knew how to code.

SIMPLE attempts to fix these issues by being open-source from day zero, by using a modern programming language, by having an architeture designed for enabling collaboration. Don’t be mistaken, though, SIMPLE does not attempt to reinvent the wheel. The real wheel is the knowledge of physics and rendering and computer sciences behind currently existing Building Performance Simulation tools… what it proposes is to build a good-old wheel with new materials and methods, in a more modern factory, and that is designed to travel in modern roads.