Monthly Archives: January 2013

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?

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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

Hello world!

Hello world! My name is Matt Doiron and I’m a bit late to the scene with this blogging thing, but I will try to make up for it. I’m a mechanical/building engineer who specializes in building energy efficiency, energy modelling and solar energy.

I’ve worked for about 5 years modelling the energy use patterns of buildings and proposing ways to make them more efficient. I also have a Masters degree in Building Engineering, which involved studying the energy performance of a low-energy, solar house.

I intend to post on various topics related to areas that I know about and that I feel strongly about. I don’t pretend to have all the answers and some issues simply don’t have good solutions today, but the more we discuss them the better off we’ll be. Continue reading