Thriving On Low Carbon

Retrofits vs. Reductions

I’m excited because I’ve been putting together a new online course on Deep Energy Retrofits (DER). More so than the course I teach on Zero Net Energy Homes, it’s focused on the multiple approaches and techniques for taking the diverse building stock we have and transforming it – not just from the standpoint of energy use, but also upgrading comfort, health and safety, and durability – because so much of our building stock is plagued with deficiencies. Retrofits fix the issues with the building asset and saving energy almost ends up as a desirable byproduct. There are so many different buildings and conditions, and therefore solutions, so the DER course is based on case studies and we show many approaches people have chosen to implement.

 If energy saving is the principal goal, it’s important to look carefully at the choices the occupants make. Energy in buildings goes to more than heating and cooling, which are the main loads that retrofits target. Over forty percent of primary energy in US homes goes to non-thermal loads. Once we superinsulate a house in New England, energy for heating, once the largest load by a comfortable margin, may become the smallest load amongst heating, domestic hot water (DHW), and plug loads/lighting/appliance loads (PLA). To get to truly low energy performance then requires focus on DHW and PLA.

 With motivated occupants, it’s possible to get deep energy reductions without DERs.  People can do a moderate weatherization on a house, then install a point source heater such as a single zone minisplit heat pump to keep the most-used part of the house comfortable. The rest of the house runs cooler and the main heating system stays off until the outdoor conditions get severe. Lots of savings have been demonstrated in this approach. Couple that with LED lighting replacement in high use fixtures; great low flow showerheads like the Delta H2OKinetic; a horizontal axis washer; and depending on the household size, perhaps a heat pump water heater. Replace the dryer with a drying rack and a clothesline. Make a concerted attempt to keep appliances and entertainment stuff off when not using it. Hunt down phantom loads. 

 Combine all of the above and the total outlay might be $10-20,000 and the energy saved might equal or even exceed what a second household might achieve that goes the whole enchilada and does a DER, if that second household is much less conscious of their DHW and PLA usage, and heats the whole retrofitted house to comfort temperatures. I definitely see DER households using a pretty wide range of energy per person. The climate doesn’t care how we each reduce our consumption, just that we do. Of course a motivated, conserving  household in a DER will have the lowest energy usage of all, but if a household is committed to reducing their carbon emissions, they needn’t spend six figures to get there. What the DER gets that the targeted weatherization, behavior-based deep energy reduction strategy may not is relief from the non-energy deficiencies – ice dams, pest infestations, water issues, mold, etc., and true comfort. The cost of remediating those defects shouldn’t have to be paid for solely by the energy savings that accrue.

 I live in a zero net energy DER after previously weatherizing a pretty good house and also reaching zero net energy. I like the second house a lot better, because of its superior comfort and air quality. But I spent a lot more money to get there, and the total energy performance isn’t much better, because DHW and PLA usage is pretty similar. The DER uses less energy for heating at an even 70F setpoint than the pretty good house used with some temperature setback and letting parts of the house get cooler. I hope to live in this retrofitted house for a long time, and it’s worth it to me to have spent what I did to get a house my wife and I are so pleased to inhabit. I’m just not fooling myself that I needed a DER to achieve deep energy reductions, if that was my only goal.

 To learn more about the transformative possibilities of Deep Energy retrofits, please join me starting September 14^th in the ten week online course – check it out at Deep Energy Retrofit online course

Photo courtesy Janice and Steve Kurkoski

 

 

 

Reflections on Building Energy 2015

For 36 years, my professional community has been the Northeast Sustainable Energy Association. This past week we gathered once again in Boston for the Building Energy Conference. It was one of the best ever. I go to Building Energy to get my mind twisted out of my ordinary fixed ideas and to learn new ways to think. This year was a bumper crop.

I took a half day workshop with Greg Norris, who is an expert in Life Cycle Assessment (LCA), which seeks to quantify the embodied energy, water, and other impacts in materials and products. He recently become Chief Scientist at the International Living Futures Institute, whose first initiative is the Living Building Challenge,  but who are going beyond that to products and neighborhoods.

In this workshop on non-toxic materials was the most inspiring thing I heard at the entire conference -  the concept of handprinting. The premise is that everything we buy or consume has a footprint, and even a vegan bike-riding solar powered person dressed in second hand clothes has a footprint – there’s no such thing as a zero footprint. In other words, a footprint represents what we take. But we can act positively as well – a simple example is planting a tree – and those actions can use the same analytic tools in many cases to tally up the give as well as the take of our selves and organizations. Handprinting combined with footprinting leads to the concept of NetPositive, giving more than we take. I found it to be a liberating construct. One exciting aspect is that the definition of what constitutes a handprint vs. a reduced footprint is yet to be fully defined in relation to buildings. When we design and build a net zero building, is the baseline the code building, or is it no building? Big difference! Thanks to Greg for doing this work!

http://www.chgeharvard.org/resource/building-netpositive-enterprises

http://www.chgeharvard.org/topic/handprint-new-unit-measuring-impact

Footprinting and LCA were embedded into the conference. South Mountain Company has been footprinting our operations - office and shop and jobsite energy, employee transportation, materials transportation. The most obvious conclusion has been that employee transportation on the Island is the largest portion by far, and we've recently re-aligned our benefits and incentives to promote higher efficiency transportation, chiefly electric vehicles. Byggmeister and SMC presented a session on our beginner's steps on this stuff, and Byggmeister's work focused beyond ours to include the embodied energy in the materials they put into place. We're starting a similar effort in analyzing a couple of the affordable houses we've built. Detailed stuff, would make even a bookkeeper's brain trip out on overload!

Howard Brown of dMass and Mark Loeffler of Atelier 10 spoke about the dematerialization of our economy. Brown was a student of Buckminster Fuller and reminds us that people want benefits not products, and every effort to deliver the benefits with less mass gets closer to the proposition of naked value, and has lower environmental impact. As Howard succinctly says, benefits are weightless. What was inspiring was the number of items they showed that last year were in development and this year were on the market. Brown emphasizes that it’s increasingly common that breakthroughs are being made by people without specialized training but rather a determination to find a better way to do something.

Examples of cool stuff:

- Piezoelectric tiles in high traffic areas like subway stations to generate electricity

- Ecovative adding to their base business of producing packing material  from ag waste and fungal mycelium to making structural biocomposites to replace materials like OSB

http://www.ecovativedesign.com/products-and-applications/structural-biocomposites/

- Concrete cloth – rolls of cloth impregnated with cement, dampen and it sets up

- Building-integrated wastewater hydropower in high rise buildings, and power from pressure reducing valves in pipelines

- Active ceramic anti-bacterial tiles - http://www.active-ceramic.com/antibacterial-tiles/

The closing forum had three old farts, I mean, friends and three young superstars each doing 20 slides in the pecha kucha technique. It was a rousing and inspiring finish to a great gathering – old guys John Abrams, Terry Brennan, and Chuck Silver, with the young-uns Stephanie Horowitz, Ace McArleton, and Declan Keefe showing us the way to the future.

I got to meet past and new students from my Zero Net Energy Homes Online Course, about to begin on Monday the 9th. And I saw hundreds of friends and colleagues, all gathered to vision a better future, and share wholeheartedly our collective experience on how to get there. If you missed BE this year, well, like the Sox, there's always next year.

Zero Net Energy Homes Course starts March 9th

3 weeks from now, NESEA and I will once again offer the Zero Net Energy Homes online course. Who do you know whose practice could really benefit from a more rigorous and quantitative understanding of building science, solar energy, superinsulated construction, ventilation, renewable energy, and low energy use mechanical systems? It's a packed 10 weeks, and includes a bunch of Excel calculators so folks can do a simple heat loss; calculate frame assembly thermal bridges; estimate hot water energy requirements; calculate the solar gain through the glazing; and do a simple annual energy calculation in order to size the PV system. In the videos I cover energy, heat transfer, moisture, thermal bridges, superinsulated construction, ventilation and heating/cooling, DHW, solar thermal and solar electricity.

As a bonus, enrolling in the course includes a membership in NESEA!

From participants:

 “I would just like to take this moment of enthusiasm and express how terrific I think this course is.”

Wayne (architect)

 “These calculators are great. The ability to tweak a couple of factors and see the whole system impact is outstanding. I feel like these are great tools to "nudge" clients towards better performing buildings as we can attach dollar amounts to heat loss....”

Bryan (design/builder)

 “The quality of teaching in your course is amazing, every word choice, how clearly the ideas are outlined, the various calculators are incredible. I'm only on week 2 and I can't believe how much I've learned.”

Lucy (homeowner doing a Deep Energy Retrofit)

 “Both NESEA and Marc have given me a tremendous leg up in my work, shortening my learning curve by months if not years in some areas.”

Newell (company president, timber framer, design/builder)

"I really, really enjoyed the course, Marc! While my wife truly grew to resent the amount of time I spent on the computer every evening, the grief I suffered was worth it. It was a real treat to have such an experienced professional open their reserves of knowledge up to anybody keen enough to listen. Most courses in energy efficient construction and sustainable design are too fluffy and general; having some math and spreadsheets to really sink our teeth into was an absolute gift. Thank you very much for the wonderful generosity of your time and attentive responses. In a world where mentorship in the construction world is all but lost, it is a terrific thing you are doing to keep the future of the industry headed down the path that yourself and your colleagues have got us started on."

Burke (builder)

Minisplit heat pumps and blizzards

A blizzard (a severe snowstorm and sustained winds of over 35 mph) is a challenging weather condition for a minisplit heat pump. Recall how an air source heat pump works - the outdoor unit has a compressor and a fan that blows air across a coil with refrigerant. In heating mode, the coil is colder than the outdoor air. As air is drawn through the coil it gives up heat to the coil and leaves the other side colder. The more humid the air (and the warmer the air is, the more moisture it can hold), the more condensation occurring on the coil. At temperatures at or below freezing, that condensation may freeze on the coil, reducing air flow through the coil and heat transfer to the refrigerant. Heat pumps are designed to sense this type of condition, and periodically operate a defrost cycle, in which the heat pump reverses and uses some energy to melt the frost off the coils. Below is the Fujitsu condenser at House 5 with frost building up:

Here's the same condenser after the defrost cycle:

Here's a Daikin condenser that I think has a faulty defrost cycle (photo taken at a house at which South Mountain has installed a solar electric system) - the frost has built up considerably:

So, the above photo excepted, this is under normal conditions, not a blizzard. Here's a screenshot of the power input to the Fujitsu at our house on January 26th as the temperatures rose and the blizzard began:

Through about 2 pm, the temperatures were in the mid-to-upper 20Fs, and the defrost cycles, marked by the dips in power draw, occurred roughly every 4 hours, lasted 4-5 minutes, and drew under 250W. Once the storm starts up, temperatures are right around freezing, and the fine snow is being whipsawed around by the strong winds, which can drive the snow into the coil, coating it and triggering the defrost cycle. The blizzard becomes a moisture delivery system. The defrost cycles are much more frequent, slightly over once per hour. And the duration rises to 15 minutes or so, with a power draw of 500W. Note also that after the defrost cycle the heat pump power draw jumps up to 900W or so, whereas before the storm it's running at 450W much of the time.  It appears that the firmware drives the heat pump up to the higher power draw for a certain amount of time after every defrost cycle, and when the cycles are frequent, it never drops down to the "cruising" power draw. So both efficiency and capacity are reduced, because the energy going into defrost isn't going into the house. You can tell when the defrost cycle occurs because the indoor fan shuts off, otherwise it would be blowing cold air.

The condenser needs clearance beneath it, because the melt from the defrost cycle is going to freeze once it drips down off the condenser, and in the worst case it freezes under the condenser and crushes the lowest row of the coil and the unit is ruined. So it makes sense to raise the condenser above snow line and keep it under an overhang or roof.

This all becomes more severe if the condenser is actually buried in snow. In the worst case, the heat pump shuts down, and we saw this at a couple of houses here. My own unit is up off the ground, and under a small roof, but the Jan 26-27 storm came from the northeast and still packed the gap between the house and condenser 40-50% full of snow. We're considering doing more wall mounted installations, getting them at least 2 feet off the ground, but architects don't want to see the condenser(s), so the inclination is to install them low to the ground and behind screening. But this usually makes them more vulnerable. Here's a neat wall mounted installation:

We've been pleased that these seem not to impart vibration to the house, the units must be very well-balanced.

Does this mean that houses heated by minisplit heat pumps, with no back-up heating system, are more vulnerable in bad storms than houses heated by modern fossil fuel burning equipment? Not necessarily - those have their own issues in the storms. Sealed combustion sidewall vents can be plugged by ice or wind-driven snow, and wind gusts can cause the pressure sensing switch to shut the units down. So modern heating systems in general are more twitchy in severe weather than the old atmospherically vented boiler venting into a interior masonry chimney, with a barometric damper. Do we want to go back to that? For a number of reasons, I'd say no. Houses that need that big boiler or furnace are much more likely to freeze up when that unit goes down (say in a power outage) than a small superinsulated house with a minisplit. My sense is, get 'em up off the ground, and check them in a bad storm.

 

Building Energy 2015 Approaches!

Mid-February can be dreary, but one bright spot on the horizon is always the Building Energy Conference in early March. It’s an annual renewal with old friends and, even better, a way to make new ones. Building Energy is so much more than information – seeing and hearing from so many others dedicated to a thriving yet lower impact future recharges my spiritual batteries as it packs my brain.

I’m excited to see the Net Zero Summit sharing our venue. On a panel called Educating the Industry with some other NESEA stalwarts, Nadav Malin, Kat Klingenberg, and Barbra Batshalom, I’ve been asked to report on my experience teaching Zero Net Energy Homes online for the NESEA Building Energy Masters Series. After five courses and over 200 participants I’m convinced self-paced, asynchronous online learning is the way to master and apply new skills and knowledge.

Speaking of zero net energy, highlights of the conference include the opening plenary on Rethinking the Grid. How will technology and policy come together to help us achieve vastly higher levels of renewable electricity? Net metering policy is changing, so what should our response be as architects, builders, engineers, regulators, building owners? There’s cool stuff on the near horizon – more affordable battery storage, and heat pumps with high temperature output. Can we envision an appliance that combines battery storage with a smart inverter/charger that knows when to store the energy and when to export it? That already exists. Yet much building energy use is thermal, but happens when the sun doesn’t shine. Think about combining that appliance with a high temperature heat pump and phase change heat storage to serve nighttime loads for heat and hot water. That doesn’t exist – yet.

BE 15 will deliver its usual “what’s new and important” message. There are some great sessions on how make less toxic, lower embodied energy material choices – I’m looking forward to learning from Greg Norris. My company South Mountain is teaming up with Byggmeister to report our experience analyzing the carbon footprint of our operations and projects. Robert Leaver and an all-star cast will help us think clearly, and make better decisions, about water in our buildings and communities, as part of NESEA’s larger focus on community resilience.

As always, BE 15 will have an abundance of techie sessions, the kind where I learn how much I really still need to learn about a topic. David White and Aubrey Gewehr will speak about managing humidity in low load homes. Chris Corson and Kohta Ueno will report on moisture loading monitoring in superinsulated walls, and Kohta will join me to chronicle our observations of minisplit heat pump performance. And I’ll do my best to embarrass myself with all the things I coulda shoulda done better on my own Deep Energy Retrofit – as has been noted, good judgment comes from experience, and experience comes from bad judgment. Like many at BE 15, I have a LOT of experience! Hope to see you there, and learn from yours.

Building Energy 2015 web page

Early Bird Deadline is midnight today for Building Energy 2015

Building Energy is the best conference I go to year after year. Design, engineering, construction, renewables, planning, with unusual peer to peer honesty and humor. Hope to see you all there!

I'm presenting a 1/2 day workshop on my own Zero Net Energy Deep Energy Retrofit, and I'm sharing a session on Carbon Footprinting Our Operations with SMC founder John Abrams as well as folks from Byggmeister. Kohta Ueno and I are speaking on minisplit heat pump performance, and I'm on a panel in the concurrent Net Zero Energy Summit on education in the ZNE world.

Hope to see you all there!

 

Net zero 2014

Utility meter read 100,691 on the morning of Jan 1st 2014 and 98,990 on the morning of Jan 1st 2015. PV meter read 12,932 on the morning of Jan 1st 2014 and 19,080 on the morning of Jan 1st 2015. We had a net export of 1,701 kWh, used 4,447 kWh, and generated 6,148 kWh. The first few weeks of the year, through early March, were spent in solving the excessive minisplit output conundrum, so had higher energy usage than I expect for the same time period in 2015 - we'll see! I'd like to see a net export of 2,000 kWh in 2015.

A visit with David Velan of Ecodrain: drainwater heat recovery comes of age

Today David Velan of Ecodrain paid us a visit here at South Mountain so my colleague Brice Delhougne and I could see his product firsthand. A few years ago David got interested in capturing the waste heat in shower water and other hot waste water. Others have done that (Powerpipe) but they have been limited to applications where the vertical heat exchanger, usually 4-6 feet long, can fit, and still be higher than the wastewater outlet from the building. Ecodrain's innovation is a wastewater heat exchanger that can be mounted horizontally.

In the photo below, you can see the inlet and outlet, which is 2 inch PVC, and the side taps for the inlet and outlet for the potable water. The unit is about 56 inches long. The flow is countercurrent - the wastewater on top flows one way, and the potable water below flows in the opposite direction and picks up heat across the copper interface. Depending on the relative flow rates, and the pitch of the unit, the Ecodrain recovers 30-45% of the energy in the wastewater.

David went through many evolutions before arriving at his product. It has a double wall heat exchanger configuration that should satisfy codes (the product has a UPC acceptance) and square section tubes on the potable water side to maximize heat exchange contact area. The upper portion of the unit is PVC and is smooth to minimize any buildup of solids. Here's a cross section:

One of the Ecodrain innovations is seen in each square tube - it's a plastic insert designed to keep the flow highly turbulent to increase heat transfer.

The bottom of the unit has a drain hole so that any leaks become obvious quickly.

The unit is designed to work with very slight pitch, like a typical plumbing waste line, but it can be pitched at more severe slopes, and the increased velocity of the wastewater increases heat recovery.

The unit can be plumbed so that the preheated water flows to the cold side of the shower, or to both the shower and the cold inlet of the water heater. The latter equal flow configuration will harvest the most BTUs.

Let's do some Marc's Sloppy Math. Say a family uses 30 gallons/day of shower water and 1/3 of that energy is recovered. That's about 625 kWh/year. At $0.20/kWh (MA residents are about to see a 30-35% rise in the supply portion of their electric bills due to last winter's natural gas price squeeze!) that's $125/year. The unit costs $440, and let's say it ends up at an installed cost of $1,000. There's a simple 8 year payback. With natural gas this will be worse. To get 625 kWh/year from PV would take about 500W of panel, which costs more than the Ecodrain installed.

One application David related to me is using the Ecodrain in cases where people are running out of hot water. Recovering drainwater heat effectively stretches the storage capacity of a water heater.

David kindly left us with one and we're looking for a good application, so we can monitor its performance in an actual situation. We were impressed with the iterative thoughtful engineering embodied in the product, it's rugged construction, and the testing Ecodrain has done to show energy recovered and its clog-free performance.

Energy Positive in First Year

We moved in on November 1st, 2013, and the PV system had been activated on October 20th. The NSTAR net meter read zero when installed, read 99980 (it goes down from zero if the energy is net exported) on Nov 8th 2013, and read 98852 on Nov 10th 2014, for a net energy export of 1,128 kWh in that year. The PV system made 6,198 kWh November through October, so we used 5,058 kWH for the year (these numbers are slightly off because of the non-simultaneity of the utility meter "year" and the fact that I read the PV meter on the 1st of each month). The monthly energy flow to and from the grid are shown in the graph below, assuming for simplicity that the NSTAR meter read zero on November 1st 2013.

Usage was a tad bit higher than I projected (somewhere around 4,700 kWh/year). One reason is the minisplit heat pump - it took me until early March to change the settings at the deeper levels of the controls that were enabling the unit to operate by cycling on at full speed then shutting down, repeatedly, working at its least efficient operating point. The subject of another post to be sure...

The eMonitor wasn't up and running until late January, so I don't have a full year's breakdown of where the energy is going, but I'd say the heat pump used almost 35% of the energy, the heat pump water heater just over 10%, and the fridge and chest freezer about 15%. The remaining 40% is cooking, water pumping (we planted several dozen trees and shrubs which we irrigated), lights, the HRV, and plug loads.

The net exported energy would power an electric vehicle for over 3,000 miles/year.

 

What we started with

This house has an interesting history. The owner of the place had been living on the lot in a structure that began its life as the body of a box truck. It was 8'x16' and had a small attached shed that housed the water pressure tank and the water heater. A small gambrel loft had been built on top - I could just barely sit up inside. There was a small gas heater, a 100A electric panel, a sink, and some built-ins. No shower. There was an outhouse on the property. You might say this was a tiny house before the Tiny House movement began.

The owner learned that there was a house in Edgartown that the property owner wanted to remove, and that he could have it for free if he moved it. The house was a stubby L shape, with a 16'x32' section that contained a kitchen, bedroom, and bathroom, and a 22'x25' section with living area. What happened is conjecture on my part - I think in haste to get the project underway that it is possible that the new foundation was put into place before the conversation with the house mover occurred. I hypothesize that the house mover looked at the 22'x25' piece and said it would be difficult/costly/impractical to move. So in the end the 16'x32' portion was severed from the rest and moved, and the 22'x25' section was duplicated new on site. All this happened in 2002-2003. I suspect the portion that was moved wasn't much older, as the glass in the Andersen windows was dated 1996, and the walls were framed with 2x6s.

The interior finish of the house was no great shakes - green carpet and white vinyl flooring, and inexpensive kitchen cabinets. There were some unpleasant odors, traceable to some rodent activity, and a 140 ft2 patch of basement floor where the water came in from the well and the pressure tank and water heater sat that didn't have a concrete slab, just crushed stone over filter fabric. Smelly soil gases. Plus, the insulation was in the ceiling of the basement, so the basement ran cold, which on MV means mold.

There was a very creative outdoor shower, complete with clawfoot tub (bathtubs are another tale in the future):

The floor plan had only one bedroom, and the south side was very modestly glazed, so we knew we were in for an interior gutting project and major re-framing of the exterior openings. Note to self - this is expensive, it's better to buy a house with a floor plan and orientation you like! Once the drywall and fiberglass were removed, it was clear there was some creative structural design incorporated. The 16'x32' portion had no structural ridge or ties across, so it was held up by paint. The rear had three substantial wood ties across at roughly 6-7 ft centers, but we needed to remove the drywall to see that each was attached to the wall with a single 1/2 inch diameter lag screw - about 1/10th of the fastening capacity the design load would merit. Good thing it hadn't seen a significant snow load.

A sensible person may ask, why did we buy this house anyway? We looked at a couple of parcels in West Tisbury (we were clear we wanted to stay in this town) and I felt that I didn't want to go through the disturbance process we do with raw land. I've been preaching that we need to fix what we have already built. I can assure you now that I have put my money, far too much of it in fact, where my mouth is. When all was said and done, we paid about $100,000 more for this house than a parcel would have cost, and we got an excellent well, a Title V compliant four bedroom septic system (this is a good thing - we could expand), two underground electrical services, one 100A serving the outbuildings, and one 200A service for the house, two funky but useful outbuildings, an excellent concrete foundation housing 1,000 ft2 of basement, and a developed site. You might say everything above the mudsills was a modest bonus - a decent floor frame in the portion built on site, a ten year old roof in excellent condition, a 12'x24' deck. Oh, and a buried 250 gallon propane tank, still mostly full of gas.

The house had a gas water heater and a gas furnace. The furnace was in a tiny attic-like spot in the 16'x32' part, and I could see outdoors through the eave vents from the furnace location. The thermal boundary was, like the framing, creative. The blower door number was a tad over 3,100 CFM50, about 0.63 CFM50 per ft2 of shell area. We aim for 0.05 CFM50 per ft2 of shell area at South Mountain and frequently do better. In this project we reduced the leakage ratio 25:1. More on that to come.