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Energy Efficient Home Design & Construction
An Expert Panel Q&A
By Jeff Cornelius - March 28, 2019
This month, we hosted our second THINKtank event of 2019 at the beautiful new Roth Living showroom near the Design Center in Denver. This THINKtank was a Q&A format focusing on energy efficient home design and construction. We were thrilled to have Casey Van-Iten of Cornerstone Homes, Zeke Freeman of Root Interiors and Enrico Bonilauiri of EMU Systems as our panel of experts. Gilda Zaragoza was our moderator.
There were many great questions and a healthy discussion from our audience members. Below, we’ve attributed answers with the initials of each panelist who addressed the question and summarized their answers for purposes of this post.
Q. What are some major considerations when designing an energy efficient home?
ZF. From a design perspective, it’s important to focus on lot siting, orienting views to take advantage of passive heating during the winter and being conscious of the materials we use. Energy efficiency is one of the reasons we build in cities. Being close to light-rail and mass transit and alternative forms of transportation all help lessen the energy impact of the inhabitants of that home.
EB. I agree with Zeke that the climate is a big consideration, including what kind of systems are designed into and installed in the home. We have weather extremes here in Colorado, along with the high altitude – this all affects how energy efficient the home will be.
CVI. There are three main areas we focus on when building our new homes. One – The design. Using passive solar design and having the correct glazing on the windows are key. Two – The thermal envelope of the home. Air infiltration and lack of proper insulation will kill a home’s efficiency. Three – the systems. You can retrofit an existing home with a more efficient HVAC system or water heater, but for something like geothermal, it’s much easier to do on a new build.
Q. Does the square footage of the home matter?
EB. More than the square footage, it’s the shape and siting of the building.
ZF. I agree with Enrico. Interestingly, we have been seeing a trend towards higher quality vs. higher square footage. Obviously the smaller the square footage, the less environmental impact there will be in the construction of it, all other things being equal.
Q. Cassie, can you speak to a home’s NetZero rating and how you are achieving that?
CVI. Sure. We focus on the HERS score. That’s a rating that considers the structure and how it’s built. Other ratings like LEED consider things like what was the property used as previously, proximity to walking and bike paths, etc. In addition to a tight building envelope and lots of insulation, we don’t use natural gas – for water heating, fireplaces or the stove in the kitchen. Using 100% electricity for our systems and appliances allows PV solar to help us achieve that NetZero rating – basically that a home produces as much energy as it uses on an annual basis.
Q. How does energy efficiency affect the budget?
ZF. You have to look at it in terms of a long-term investment. There is a slight premium up front, but those costs are recouped over time in the form of energy cost savings.
CVI. Engineering, windows, insulation and systems are all more expensive than average, but it is a long-term calculation. And, the government keeps extending tax incentives, so that helps make things more affordable up front.
EB. Yes, the incentives that are in place are really helping multi-unit developers because at that scales, they are reaching almost parity to non-efficient construction and systems.
Q. What products give you the most bang for your buck?
EB. I would say high-performance windows. I especially like Alpen windows, which is a Colorado-based company.
ZF. We compared a 2x4 studded wall with 2” of exterior insulation vs. a SIP vs. a 2x6” studded wall with interior insulation and the 2x4 was most cost-efficient in terms of R value in our test. That may not always be the case for some projects, but my point is that it pays to look at things on a project-by-project basis and not just assume a SIP will be the most efficient for a wall.
CVI. We can get the same R values with stud and insulation vs. SIPs. Smart window shades and thermostats can help. Solar batteries are improving, too.
Q. Are there any products we should stay away from?
EB. Poorly installed ones. (lots of laughs). Yes, it’s funny I say that, but its true. There are lots of great products on the market, but they need to be installed properly to achieve your energy savings goals. It gets more and more critical as you approach NetZero.
Q. How do you incorporate landscaping into energy efficient design?
ZF. You can do this by planting deciduous trees in front of south-facing windows. This provides shade in the summer and sun in the winter. Xeriscaping can drastically reduce water usage as well.
CVI. You can design drainage the feeds landscaping vs. draining on an impervious surface. Also, have goats! They are great lawnmowers!
Q. What is the difference between passive solar and a passive house?
EB. Passive solar helps reduce the need for heating whereas passive house is a construction standard for air leakage and energy consumption.
CVI. Another standard that is growing in popularity is the Living Building Standard – it takes into consideration the overall wellness of the occupants, not just energy efficiency. As in “do these lights make you happy?”
Q. Do you have any Colorado-specific considerations?
CVI. We see dramatic temperature swings here, so a tight building envelope is key. Also, water conservation is particularly important for us in Colorado.
ZF. As we’ve discussed, house siting is really important here in Colorado to account for the movement of the sun through the seasons, snow gathering, etc.
EB. High-performance windows can really help.
Q. What information sources do you like to stay current on energy efficiency?
CVI. I get the USGBC newsletter – they have an office in Denver. Also, check out the LEED website – lots of good info there.
EB. Check out PassivePedia – it’s like Wikipedia, but for energy efficient construction.
ZF. Hammer & Hand out of Washington. Building Science is an online magazine. The Zero Energy Project. Also, the US Passive House website is a great resource.