Version Control for Energy Models

I mentioned in a previous post that I was experimenting with version control for energy models in my daily work. I’ve been using Mercurial and TortoiseHG ever since and I’ve learned a significant amount about how version control tools can be useful in energy modelling. In this post I describe in more detail my own version control workflow, and its pros and cons. Continue reading

IDF+: An Enhanced Editor for EnergyPlus Input FIles

IDF+ Screenshot

IDF+ Screenshot

In a previous post I set out my “Manifesto for Good Energy Modelling Tools“, in this post I wanted to share an initial public preview of a tool I’ve been working on. The tool is an enhanced editor for EnergyPlus idf files. In creating the tool, I’ve attempted to embrace the concepts in the manifesto (rather, I discovered and developed the concepts as I created the tool). I use the official IDF Editor that comes with EnergyPlus every day—it is the primary tool I use for interacting with IDF files. I have come to respect it and think it is probably the best tool out there right now for working with IDF tools, however, it also has some significant limitations that I decided to address. The working name I’ve chosen is IDF+, but I am hoping to find something a bit more original as development progresses (suggestions are welcome!). Continue reading

Manifesto for Good Energy Modelling Tools

For the last eight to ten months I’ve been thinking about and working on tools to help improve my energy modelling workflows. In the process I’ve analyzed my current tools and found them to be lacking in certain areas. I’ve also not been able to find any other tools that really meet my expectations. Throughout this process I’ve identified some key characteristics and concepts that I value in energy modelling tools and will describe them here in a “Manifesto for Good Energy Modelling Tools”.

Continue reading

New Job, New City and 6,000 km

I haven’t posted in a while, but I have a good excuse! My family and I have moved from one coast to the other for a new job, new city and new adventures in building energy modelling. The new job has been great! I’ve been learning EnergyPlus, which is a tool I have wanted to dive into, and I have also continue to learn about LEED and compliance-type modelling. It makes a difference to be surrounded by other modellers, and also by those doing other types of building simulation.

EnergyPlus is certainly an impressive tool, but it also has its downsides. We use the bare IDF Editor so there is no fancy interface. This makes for a steep learning curve, but also forces you to really understand what’s going on in your model. There are also a wide range of tools that make the task easier – like a good text editor, file merging/comparison tools, SketchUp for geometry editing and results viewers.

In future posts I will try to document some of my journey to learn EnergyPlus so that others can benefit from it.

Pragmatic Base Year Selection

Base year selection can be a challenge in a real building, but a pragmatic approach can make things easier. As discussed in my previous article, 10 Steps To a Useful Energy Model, a base year is a representative year of building utility data used to help calibrate/validate an energy model. It is also used as a starting point to judge savings when applying energy retrofits to a model.

There are various ways to perform analysis of energy data while selecting a base year. A few of them will be covered here, but on real projects, with real buildings, there will often be a very easy way to select a base year – the only year of data you have. When asking for energy data it’s common to request three or more consecutive years worth. This is not going to happen every time. If less than twelve months of data is provided and the client desires a full, whole-building energy model, it may be very difficult to achieve a satisfactory accuracy. Continue reading

Adventures in LEED Energy Modelling

I’ve been super busy over the last month or more – between our 7-month-old and work, it’s been crazy! Work for me lately has been all about LEED Energy Modelling and ASHRAE 90.1 Appendix G. For those of you who may not be aware, a significant number of LEED points are up for grabs related to optimizing energy performance in a building. The basic procedure is to model a strictly defined reference building, your proposed building and then compare the two. The percent difference defines how many points are awarded.

This was only my second project like this (I also did a project to judge energy performance against MNECB) and I have found it very enlightening! The vast majority of energy models I’ve done in the past were for the purpose of judging the impact of energy retrofits, so these models were all of existing buildings, calibrated to a base year. At first glance, an energy model is an energy model, but when you get into the details, I was surprised at how fundamental a difference there could be between the two concepts. Continue reading

Making Good Assumptions For an Energy Model

Modelling an existing building has unique challenges. In some ways it can be easier than modelling a building that doesn’t exist yet because everything is fixed – there is no architect, engineer or owner to make last minute changes. Other aspects are more difficult, however, because reality is often “messy” and full of unknowns. No matter how detailed an audit is performed or how many piles of drawings are available, there will always be significant information missing. It’s not just simple quantities like the insulating value in a wall either. It can sometimes be complicated values such as the cycle times and loading of compressors, pumps or other equipment. This requires making assumptions and modelling based on these assumptions. The outputs of the model are dependent on the assumptions input, so making good assumptions can mean the difference between a model that fulfils its purpose and one that doesn’t. A model for a large building can involve dozens of assumptions – how can so many unknowns be filled in reliably?

Continue reading

Air-sealing is Good, But Don’t Forget The HRV!

We all know what its like to work or live in a drafty building, or what it’s like to pay a larger-than-it-should-be energy bill due to extra heating or cooling. A common solution that is recommended to building owners is to seal the cracks in their walls, windows, doors, etc. It’s true that in many cases this air-sealing provides great “bang for your buck” in energy savings, but without proper understanding of the system that is your building you may end up with more problems down the road than just high energy bills! Continue reading

10 Steps To a Useful Energy Model

In today’s world of high-tech buildings, increasing energy prices and ever-more-stringent building codes, designing and maintaining a building is complicated. Many governments (municipal, provincial/state or federal), institutions and companies are realizing the potential benefits of reducing their energy and resource use. From simply saving money, simplifying production lines,  and being environmentally responsible, to marketing and public relations exercises, there are many reasons to want to understand the energy use patterns in your buildings. An energy model is an excellent way to do this and can be applied at any time during the life-cycle of a building. Ideally, modelling would come into play very early in the design phase, but there is still great value to be found later when energy retrofits are being considered.

An energy model is simply a mathematical (software) representation of a physical building – one that already exists or one that is being designed. The model is a tool for simulating what will, could, should or would happen in real life if the exact circumstances of the model happened in reality. This gets complicated very quickly, as obviously it can be very difficult to know what is or will actually happen in real life. Anyone new to building energy modelling might look at a finished model and feel overwhelmed at the shear amount of information that goes into a good model. Like driving a bike or a car, however, once you get the hang of it you won’t feel as intimidated by the details.

I don’t want to claim that there are only 10 things to do in order to create a useful energy model, because sometimes (if not most of the time) there are many more. For someone getting started though, these 10 steps should help clarify the types of tasks, documents, information, tools and other resources that are required to create a useful model of the energy use in a building. Continue reading