Category: Lessons Learned
I built a large traditional open-hearth fireplace in THE HAYFIELD HOUSE. Unfortunately, it didn’t work! Following is my story of how I ‘fixed’ the problem. I built a house in 1990 with a large traditional open-hearth fireplace. That fireplace worked great, so I used that design to build a similar (but bigger) fireplace in THE HAYFIELD HOUSE. Unfortunately, my new fireplace didn’t work very well. Smoke tended to back-draft into the living area instead of rising up the chimney. What was worse is that if any exhaust fans were simultaneously working (kitchen fan, etc.), the entire house would fill with smoke. And of course, my smoke alarms were constantly being triggered. In short, the chimney wasn’t drawing well. –What I had failed to understand was...
The building of a net-zero house requires the forecasting of both the energy production and energy demands of the house. There are computer software models that can be used to make these forecasts. However, these models can have issues. Forecasting energy production (at least for solar panels) is generally quite accurate. However, the forecast for the energy demand of a house have high error ranges. Part of the problem is the difficulty of predicting how an owner will actually use the house. For example, one owner might be frugal in his energy use, while the other owner turns up the heat to 75 degrees. Over-all, the models have a wide error range with a bias to over-estimating energy use. For example, Applied Energy Volume...
A SECRET RECIPE TO GET TO NET-ZERO??? One of the reasons why many homebuilders shy away from building a zero net-energy home is that it sounds so complicated. The various experts don’t help with their barrage of technical advice on building design, insulation strategies, computer modeling, inspections, auditing, testing, etc. Furthermore, a discussion of incremental costs is frequently lacking. — Instead, homeowners just want someone to tell them in simple terms how to get to net-zero, and what it will cost. What’s the secret recipe? The best recipe that I’ve currently found is provided in the book The New Net Zero, by William Maclay and Maclay Architects. Their recipe is based on experience, so I expect it works quite well in the Northern New England...
HOW MUCH EXTRA DOES IT COST TO BUILD A ZERO NET-ENERGY HOME COMPARED TO A CODE COMPLIANT HOME? This is a much-debated question, with typical answers suggesting the incremental building costs to be within the range of 6% to 20%, see table below. My guess is that many authors consider the 20% number an outlier, but I’m not convinced of that based on my experience building a custom ZNE house. So as not to keep you in suspense, it cost me at least $112,000 extra to build THE HAYFIELD HOUSE to be zero net-energy versus merely code compliant. This equates to about 14% extra. This figure represents the initial incremental gross upfront building costs prior to any tax incentives, rebates, or avoided energy costs. Note: my...
WHY ZERO NET-ENERGY WASN’T GOOD ENOUGH FOR MY HOUSE Many zero net-energy advocates make the statement that ‘zero net-energy homes have zero energy costs’. There is a dirty little secret that made this statement false for THE HAYFIELD HOUSE. Following is my story and the dirty little secret. The definition of a zero net-energy home is one that produces as much renewal energy as the house uses, as measured on an annual basis. It then sounds logical to jump to the conclusion that such homes have zero operating energy costs. It also sounds logical to assume that if a house is performing at near zero net-energy that your utility bills will also be near zero. — I’ve found both assumptions to be FALSE for THE HAYFIELD HOUSE....
Air Source Heat Pumps versus Electric Resistance Water Heaters — Lesson Learned. You’ll find that many zero net-energy (“ZNE”) homes use a ’high efficient’ air-source heat pump water heater (“HPWH”). Many net-zero authors recommend these systems as part of the over-all strategy to lower the home’s energy demand. This recommendation sounds logical, especially when the EnergyGuide label on such water tanks advertise several hundred dollars of annual savings compared to other less efficient systems such as electric resistance water heaters (”ERWH”). In addition, many jurisdictions are trying to encourage the use of HPWH systems either via incentives or regulations. BUT, WHOA NELLIE, HOLD YOUR HORSES!!! These air-source systems aren’t as good as advertised and may not be your best option to heat water, especially...
NET-ZERO BUILDING…. How to get there. Constructing a zero net-energy house that uses zero fossil fuel might sound hard, but it’s easier than you’d think (which is one of the reasons why I started this blog). Not many people have tried to construct a zero net-energy house. The Rocky Mountain Institute states in their 2018 paper “Economics of Zero-Energy Homes” that; “… ZE (Zero-Energy) and ZER (Zero Energy Ready) homes comprise less than 0.1% of the current US housing stock”. Deduct from this figure the zero energy ready component (which likely is the largest component), and further deduct any house that uses fossil fuels, and you are left with a very tiny (unknown) number of net-zero energy, zero fossil fuel homes. One can also visit...
[…] I also knew nothing about air-source hot water tanks that are used in many ZNE homes. That was OK,…