More and more, we are hearing the buzzwords of sustainability, low energy consumption, green energy and resilient design. But for many of us, that’s all they are – buzzwords. There are also many energy goals for cities, states, countries and the world, but how does that apply to you?
A lot of people think that to make a difference you have to have big energy reduction goals and complicated systems. While you can certainly do it this way, you can also make some simple design decisions early in the process that can have a positive effect as well.
One of the most effective strategies is to identify and define your sustainability / energy reduction goals as early as possible so that they can be incorporated early in the project design. This helps the design team understand your expectations from the start. With a goal to achieve, they can frame the appropriate design solution. You’ll get the best result, the lowest implementation cost, and the most efficient integration of design efforts into your project.
Site selection and building orientation are also extremely important when designing a new building. Knowing how to use the sun to your advantage for daylighting, passive heating and solar energy is important. If possible, avoid orienting the long dimension of your building on a north / south axis, which will cause your sun exposure to come from the east and west. This orientation maximizes the building’s exposure to the sun when it is lowest in the sky, creating a lot of weather with unwanted and unpleasant reflections, blinding occupants and forcing them to use blinds or other covers. windows, which mitigates the benefits of daylight.
If you orient the long dimension of your building on an east / west axis, you have more possibilities to harness the power of the sun. To use the sun to their advantage, many low-energy, resilient building design teams choose to include louvered windows. Slatted windows are typically located on the north wall at or near the roofline and above adjacent roofs. This design feature helps bring in natural light while minimizing unwanted glare, improving occupant satisfaction and productivity. It also helps reduce energy costs for lighting the space if used in conjunction with daylight sensors and automatic lighting controls. Another advantage of an east / west orientation is the installation of solar panels or the use of passive solar heating on the south facing wall due to the increased exposure to the sun.
Another important design decision that is often made early in the design process is the massing of your building – in simple terms, it’s the shape of your building. As a general rule, the more compressed and simple in shape a building, the more energy efficient it will be. Conversely, when a building has many irregular bumps or is built around an outdoor yard, it is less energy efficient to heat and cool with your HVAC system.
Because each project has nuances and specific needs that drive the design, high level, âblack boxâ energy modeling comes into play. Your architects and engineers can work together to create and compare digital models of various shapes. basic building at different orientations on your site in order to identify the optimal combination. The energy modeling at this point focuses on the geographic location, the orientation of the sun throughout the year and the quantity, size and location of the windows to find the best combination to meet your sustainability goals / energy reduction.
Once you have chosen a combination of orientation and building volume, move on to designing your building envelope to further minimize your heating / cooling losses and energy consumption. The envelope of a building consists of the roof, exterior walls, sub-floor, floor, windows and exterior doors. An important aspect of the envelope which is often overlooked and which has a significant impact on energy efficiency is its ârigorâ. A sealed envelope limits the infiltration of outside air into the building and controls its distribution. A very tight envelope can reduce energy consumption by up to thirty percent on its own.
Insulation in a building envelope is another energy reduction factor. The good news is that the energy code relating to insulation is increasingly aggressive with its requirements. The most important thing to consider with insulation is that it be as continuous of one layer as possible.
Windows are another element of your envelope design as they play an important role in natural lighting and passive heating. When looking at windows from an energy perspective, pay close attention to the U factor and the Solar Heat Gain Coefficient (SHGC). The lower the U factor, the better, because it means that it does not conduct heat very well and is thermally insulating. SHGC is a sophisticated industry term for a window’s ability to pass radiant heat from the sun when direct sunlight hits glass. On your south-facing windows, you generally want a high SHGC to pass through as much radiant heat as possible to maximize passive solar heating.
On windows that face directions other than south, a lower SHGC is desirable to allow less radiant heat through. There are other factors, such as seasons, to consider when making decisions about window performance criteria. Overall, your design team should look at window overhangs and other specially designed shading devices to keep the sun out when trying to cool the building in summer and let heat in when trying to heat it. in cold weather. month.
Each item discussed has a different impact on your building’s dependence on energy for heating, cooling and lighting. These elements also have a direct impact on the resilience of your building. Resilience is the ability or ability to recover quickly from difficulties, and when a building is designed and constructed to operate successfully with minimal energy input, it becomes inherently more resilient. It also helps extend the life cycle of your mechanical and electrical systems, which are also more resilient. This puts less strain on local utilities and distribution infrastructure, which also helps them become more resilient.
The main thing to remember is this: instead of just investing more money in an expensive and complicated HVAC system to fit a particular design, take the time to make thoughtful decisions early in the design process when they are needed. can have the greatest impact on your building’s performance and the least impact on your budget.
By Cole Carlson, PE, CEM, LEED AP BD + C Mechanical / Energy Engineer, Obernel Engineering