O.D.E.S.A

High Performance Homes

By Michael Payne

O.D.E.S.A. an acronym for high performance.

Not to be confused with Odessa Ukraine, or Odessa, TX, this is an easy to remember acronym that establishes the sensible order for considering the process for designing an energy efficient home. The O. stands for Orientation, primarily to the compass points for taking advantage of natural solar heat gains. The D. Stands for Design, where should the windows be? Where should deep overhangs be? The E. stands for the Envelope of the building, insulation requirements, as well as the window types. S. stands for Systems, HVAC, electrical, etc, and the A. stands for Alternant energy additions, like solar, wind and geothermal. We will cover each of these in more detail. This article is just a start, please continue the journey!

We office out of Lakewood Colorado and provide plans for municipalities all along the Front Range, particularly the Denver metropolitan area. As a home rule state, Colorado allows each municipality the independence to provide code alternations and modifications. This keeps us busy tracking the various ICC code publications. Some are using the 2009, 2012, 2015 and 2018. Recently we attended classes put on by the Colorado Chapter of the International Code Council (CCICC). The documents they taught from were the 2021 publications. Several of the local jurisdictions have or will soon adopt (with their own amendments) these codes. There are significant changes to the IECC requirements which we will briefly address later. Most of our work is with existing housing stock, so we are seldom able to address the two most critical of the O.D.E.S.A.’s acronym’s influence, Orientation and Design. Daily historical weather patterns in Colorado often have sunny mornings and cloud covered afternoons. Being in the northern hemisphere, the best orientation is to have the longest wall face directly south or 15° east of south. This allows the winter sun, at its lower angle to heat the southern wall and if windows are properly placed, heat the interior space as well. You will need to know your local weather patterns to see how to best orient your projects. Terrain, trees, driveway access all provide limitations to the best orientation. We have learned that if we can have a south facing driveway and entry, we have much fewer issues with snow, as the sun does a wonderful job of helping with snow removal. Something to keep in mind when purchasing or building a home.

The second item in the acronym is Design. Again, since most of our work is with existing stock, and in developed areas, there is little that we can do to influence the design, unless the project is a scrape, or we are adding a “pop top” the Colorado vernacular for adding a second story. Consider large windows facing the south, and smaller windows on the north side, limit the number of windows on the east and west to block out the early and late afternoon sun, which while it is milder than mid-day sun, can add quite a few BTU’s. Light shelves can get reflected light deeper into the building without the heat gain, Trombe walls and heavy dense materials act as a heat sink, and distribute heat in the

cooler part of the day. Material color choice also can affect heat retention or reflection and should be chosen for the desired effect for your climate. As alluded to above, rectangular houses can take advantage of the sun better than square houses.

The third consideration would be the Envelope. And it is here where we begin gaining the influence of the Code, particularly the IECC. How much insulation should be in the walls, ceiling, floor, under the slab, and does it make sense to increase the R-factor with thicker walls or higher density insulation? Should the windows be upgraded from code compliant to something with a lower U-value? We will not discuss the economic trade off, of spending more now for lower utility bills in the future, but one definite benefit of a better built home is occupant comfort. With the windows and doors available now, it is no longer necessary to move away from a window when the wind is howling. Recent code releases have begun to address sealing the envelope along with the increased insulation requirements. This was one of the focal points of the CCICC classes we attended. We will be providing some of the details for sealing in the AIBD member only detail catalogue CAD Design Details » American Institute of Building Design (AIBD) Among the details that are provided you will find wall sections, as well as Structural Insulated Panels (SIP) to assist you in designing an energy efficient envelope. Example Project using the 2018 International Energy Conservation Code (IECC)

Projects that are in Climate zone 5 and under 2018 IECC are required to have the IECC Table R402.1.4 on the drawings (See Figure 1). This can be on the front/cover page or could be on an IECC page in the drawing set. We put it on the cover sheet as it is a check off for review.

Our jurisdictions require us to include a Building Envelope Drawing, this is a sample of what one looks like. Note we have pulled it from the reference in Figure 2.

Figure 3 is the IECC Table R402.4.1.1 it describes the sealing criteria and installation details

Also, in the drawing set or on an IECC page we need to have a Building Envelope Drawing with plan view of the thermal envelope, see Figure 4.

The 4th consideration from the acronym above is Systems. My earlier interpretation of this limited it to heating and cooling systems. As these are the greatest consumers of energy within our residential structures. A high efficiency heating system whether it’s a boiler or forced air unit is important. The system also needs to be balanced, with enough airflow to the various portions of the house to

Figure 1: IECC Table R402.1.4

AIBD catalogue CAD Design Details:

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provide for comfort. Domestic hot water use it’s also an item of concern. Recirculation pumps and pipe insulation should be considered. In the 2021 IECC, it is suggested that all areas that need hot water be placed in close proximity. Another system worth consideration are energy recovery ventilation, and heat recovery ventilators. The last system I will mention, is looking at the electrical wiring switching and lighting as a system. For several code releases lighting control has been considered for the commercial market. But in recently issued 2021 version, lighting controls are recommended. These can be occupancy sensors dimmer switches or timer switches.

Alternate forms of energy is the last item we will discuss. Because of the visibility of the alternate systems, and the ability of alternate systems to make people feel good about

Figure 2: Building Envelope Drawing

Figure 3: IECC Table R402.4.1.1

what they’re doing to help the environment, this is often one of the first things that people will do to upgrade their home to a more energy efficient home. Liquid based solar heating systems have been the most efficient of the systems. But they don’t have a long-life span, and I think we’ve all seen abandoned hydronic systems which are an eyesore. Photo-voltaic panels are what you see most of the time. But wind energy and ground source energy heat pumps are also sources of alternate energy.

The most important to think about is: Can we use the heat of the sun to help us with energy consumption?” The next most important thing to consider is how to design the building to take advantage of the weather conditions sun orientation and client needs, not necessarily in that order. We have a great deal of control over the envelope of a structure. Insulating the envelope, sealing it, choosing proper materials and proper colors as well as choosing efficient windows help us achieve reduced energy use. Systems also need to be designed for the most efficient use of energy, and finally once we have reduce the energy demands of a structure then it is time to consider alternate energy sources.

So keep in mind O.D.E.S.A. when designing for energy efficiency. Happy Designing!

Michael Payne

is a partner at Empire Design & Drafting, LCC. He is also an AIBD Board of Directors and the Chairman of the AIBD High Performance Home Team

Figure 4: Building Envelope Drawing with plan view of the thermal envelope