THE HAYFIELD HOUSE

A Homeowner's Quest for Sustainable Building

Category: Design

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Battery Back-up / Costs / Design / Lessons Learned

WHY I DIDN’T INSTALL BACK-UP BATTERIES IN MY NET-ZERO HOUSE

THE HAYFIELD HOUSE was completed in 2019, but I didn’t install back-up batteries then. At that time, my solar company advised me to wait a few years before deciding on whether I wanted to install back-up batteries. Their reasoning was that the upcoming 2nd generation storage batteries would be much better (and maybe cheaper) than the existing batteries. I took their advice and waited. Here is what happened and why I still don’t have batteries. In 2019, I thought I was being quite smart as I planned ahead for my future batteries. I had left space along my garage wall (near my inverters and electric meter) for my future batteries. In addition, my 400-amp electric service contained two 200-amp panels, one of which could serve...

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Air source heat pumps / Design / Heating / Insulation / Lessons Learned / Performance Metrics / Sustainable Building

It’s Important to Measure the Performance of Your Net-zero House. — I’m glad I did.

Measuring the performance (“EUI”) of your zero net-energy house is important. There is a saying, “You can’t manage what you don’t measure”. Without measuring, you don’t know how energy efficient your house is. Fortunately, I measured and found out my house wasn’t performing as expected. What did I measure? What did I find? And how did I fix the problem? The standard metric to measure the performance of a net-zero house is to calculate the energy-use intensity (“EUI”). As a refresher as to what EUI is and how to measure it, click here. Ideally, the EUI for a zero net-energy should be below15, and definitely below 20. The EUI for THE HAYFIELD HOUSE is about 15, but I wish it was even lower.– I’ll explain...

Air Exchange / Design / Fireplace / Lessons Learned

Fireplaces don’t work well in net zero houses

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...

Air source heat pumps / Design / Lessons Learned

Use Outputs from Energy Modeling Software with Caution

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...

Blower Door Test

Design / Insulation / Lessons Learned / Performance Metrics / Sustainable Building / ZNE Homes Examples

What’s the Secret Recipe to get to Zero Net-Energy

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...

Design / Sustainable Building

ALL HOMES WILL EVENTUALLY BE ZERO NET-ENERGY

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 ZER 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 carbon homes.  One can also visit the Net-Zero Energy Coalition (www.netzeroenergcoalition.com) and the New Building Institute (www.newbuildings.org), both of which attempt to track these types of numbers, but their figures are more useful in gauging trends, not absolute numbers.  Although the present number of zero net-energy (“ZNE”) homes is low, eventually nearly every new single-family house...

Costs / Design / Financial / Lessons Learned

HOW MUCH EXTRA DOES IT COST TO BUILD A ZERO NET-ENERGY HOME?

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...

Design / Lessons Learned

WHY ZERO NET-ENERGY WASN’T GOOD ENOUGH FOR MY HOUSE

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....

Design / Solar

SOLAR PANELS AND PROPER ROOF DESIGN AND VENTING

SOLAR PANELS AND THE INVASION OF THE ROOF VENTS Currently, most solar panels are installed on existing houses; but what a nightmare that can be.  Older roofs were not designed in anticipation that solar panels would be added later.  Therefore, many older roofs look like this.  What a mess!  This roof can barely fit any solar panels due to the interference with the vents. — Vents are a solar panel killer! Another problem with many roof designs is a frequent abundance of gables, peaks, valleys, ridges, dormers, offsets etc. These (sometimes superfluous) architectural features limit the number of solar panels that can be installed.  Take the pictured roof (below) for example.  It is a southerly facing roof with excellent solar potential, except for the fact...