What is a our earth tube really contributing?

A deep dive into earth tubes with a detailed look at the data collected on the Walton house. A Passive Buildings Canada presentation, part of "High Performance Design Meets Boots on the Ground" - Toronto Ontario, March 11, 2020. Presenters: Yury Petyushin & Rob Blakeney.  Earth tubes are praised by some people as an infinite source of absurdly cheap energy and are cursed by others as a health hazard due to the potential risk of mould growth. How many earth tubes have been installed in Canada and how are they operating? What is data really showing us? After analyzing more than 300,000 data points from a real project, Rob and Yury are ready to share the results.

Are you still pleased with the performance of the CERV2?

A question that has been posed in one form or another, numerous times, deserves a more nuanced answer than just 'Yes'.

First I would reframe the question. The CERV2 device, while it is an essential component, is only part of an overall design contributing to our indoor environmental quality. So my observations applies to the system performance.

Pro

• uniform comfort throughout the home - awesome
• quiet
• clean - MERV13 filters slash housekeeping chores
• peace of mind to know that 'invisible' health factors such as PM2.5 particulates, VOCs, CO2 and humidity are being monitored and managed
• works great out of the box with virtually no intervention needed yet allows tweaking for seasonality and home operation. 
• service and software upgrades are simple. We had a software and chip issue on the CERV that were promptly and easily addressed.
• incredibly efficient - in combination with the earth tube the CERV heat pump COP is optimized.
• the folks at Buildequinox are responsive knowledgeable and thorough.
• rich data acquisition and online reporting and control is outstanding.
• the CRV design is robust, simple, serviceable, efficient with quality components. 

Con (pretty much nitpicking here)

• CERV2 hasn't addressed a full Centigrade interface - its a Canadian thing.
• the fasteners on filter covers don't convey the underlying quality of the CERV
• the ducting design has to be done right the first time and the flow rates are bit out of 'normal' for HVAC installers. We are slightly warmer upstairs than down and can't quite balance it out.
• the inline resistance heater is a bit mysterious to setup and monitor although ultimately is just works.
• duct noise levels at night are more noticeable - comparable to a regular furnace install - but purely subjective as it is mostly me that thinks there should have been more duct muffling. 
• there are a few 'tricks' to learn such as dehumidification by lowered max temperature.
• there are few data points that aren't collected in the data acquisition such as outdoor temp in addition to intake temp.
• manual inspection of filters needed - pressure differential alarm would be sweet. 

Further thoughts...

Part of the IEQ equation is the Heat pump water heater and heat pump clothes dryer. These both contribute some heating/cooling and dehumidification. Our indoor plants contribute some humidification. One of the fascinating aspects of PH is how responsive the indoor environment is to small input changes.

In our experience, we have found Buildequinox are uniquely committed to leading-edge development of residential IAQ management and high-performance home design in general. They offer a constantly updated archive of related article and videos that are required reading if you really want to appreciate the complexity of optimal IEQ design. https://www.buildequinox.com/news/ and  https://www.buildequinox.com/publications/

Another thoughtful, leading-edge source of information on the topic is Nate Adams. Nate draws knowledge from many of the leading thinkers and practitioners in the field and applies it in a practical accessible methodology. Download his 'Understanding your home heating and cooling system'  for some revealing tips and recomendations. http://www.natethehousewhisperer.com/hvac-101.html

Inside and Out Podcast interview on Passive House with Peter Smith

INSIDE AND OUT: Talk with CHRIS LEE, environmentalist, farmer, volunteer, about his and Judy's PASSIVE HOUSE in rural Ontario. Almost zero carbon footprint, cost and energy-efficient. Passive idea works in new builds, retrofits, and renovations. Time to get real about climate and HIGH PERFORMANCE BUILDINGS can help us get to where we need to go. Give a listen. Inside and Out are conversations with those impacting on the world in grand, eloquent, and loving ways. Here is a link for it: https://anchor.fm/peter-smith05

 You can also listen in on: Spotify, Apple Podcasts, Breaker, Google Podcasts, Pocket Casts, RadioPublic, Copy RSS under the In No Particular Order banner. email: innoparticularorder.podcast@gmail.com

Hunting for where the heat goes.

We had the opportunity to do an infrared scan of the house on a dull January day at outdoor freezing temperature when the loss prevention technician from our insurance company was here for an assessment. He is an experienced operator with professional equipment. None the less this was just a quick scan and should be interpreted with caution.

The second law of thermodynamics gives us the heads up that heat will eventually move from the warm interior to a cold exterior. IR scans point us to where this is happening and help us check on how much and how fast this is happening (despite our best efforts).

No startling revelations but several interesting observations.

• the scan is sensitive enough that the interior 2x4 studs are evident even behind 8" of EPS insulation, siding and two layers of OSB! It also confirms the contribution of 4" of blown-in fibreglass.
•  the overhang roof surface show 'warm' but I assign that to residual environmental heat and the surface change, going from the wood siding to the black rubber shingling. flir0082.jpg
• I may need to adjust the main door latching. flir0083.jpg This may be a trace heat signature of having opened then closed the door letting heat escape.
• The door latches are thermal bridges (we already knew that having observed some interior condensation on the deadbolt knob in cold weather). flir0083.jpg   
• the interior ceiling corners still show a 5C temperature differential despite heroic levels of insulation. It really drives home the difficulty of dealing with complex architectural features such as the lower floor ceiling corner with the setback of the upper wall corner.
• our Vetta windows are all performing consistently. The glazing may be better than the frames - we already anticipated that as we went with the most economical window. But the Elite 92 at 0.8 W/m²K still sneaks under the passive house bar.
• it is revealing that the CERV2 exhaust shows as 'cool' on the north side (upper right on flir0085.jpg). It is a tribute to the efficiency of this unit that the exhaust air appears very close to ambient outdoor air temp.
• no leaks in evidence!
•  ⛄
•   

Summer chilling and observations for a hot sticky week.

The last week delivered sustained heat with peak temps in the 30C+ range (90F ish). Inside? The top blue line in the graph below tells the story. The setpoint for cooling is at 75F so you can also see that the CERV only cools part-time but has been effective when needed.

The lower greenish line records the effect of the earth tube in reducing intake air temp.

How about humidity? The bottom pale blue line is house air bumping along at 60-70% RH when the humidex was 40+.  The top line is the Relative humidity (RH) of the intake after transiting the earth tube. The reason for 100%RH is that this air was hot and humid at intake and during transit, the temp dropped raising the RH and condensing (dehumidifying) in the earth tube. The earth tube has a slope and a drain to cope with condensate. I have been monitoring it and all is operating as designed thus far. 

The window overhangs have been doing their job. With the passing of the solstice, the sun will penetrate more over coming weeks but for now, it barely has an effect after 10am.

NOTE: My apologies in advance for the confusing temperature scales. While our CERV2 is an amazing device, it is made in the USA and has not yet been taught to play nice at all times with Centigrade temps and the metric system.

Daily power consumption for the entire house including cooling/ventilation is running at little over 10kWh or about $1 a day.

Comfort - does it have to be so boring?

No question this is the most comfortable home we have lived in but I still struggle to get my head around the lack of doing something -anything to adjust - this is boring! The thermometer just doesn't move significantly, the CERV2 data logging is charting flat lines of temperature. I have looked for and can't find cool spots, draughts or even condensation in even our most adverse winter conditions.

We have conditioned ourselves to fiddle with the thermostat and worry about the humidity but in reality, there is much more to it. One of the many benefits of passive house design is that comfort is built right in. So what are these factors that passive house design accounts for? Turns out that while the solution appears simple, the science is complex.

The basics of thermal comfort

Thermal comfort is a subjective state. It is both psychological and physiological, and as such is one of the most complex but important aspects of building design.

There are three types of heat transfer: conduction (transfer through direct contact with solid materials, like holding a hot cup of coffee), convection (transfer through liquids and gasses, like feeling colder when it’s windy) and radiation (transfer through electromagnetic waves, like feeling hot when close to a fire).

In addition, there are six factors that influence thermal comfort:

Indoor environmental quality is top of mind in a tight house and me with a background of environment sensitivities.

'Smart' ventilation is a whole new world after living in a legacy home that was freely 'ventilated' with a generous amount of 'leakage'. The CERV2 from Build Equinox is a vast leap forward in terms of healthy, comfortable indoor air quality and amazingly efficient at the same time.

Efficiently maintaining a healthy indoor environment is complicated. Automatic control, or “smart ventilation”, is important for meeting a home’s dynamic fresh air requirements while relieving the

 home occupants’ stress worrying about air quality. Effective distribution of fresh air within a home is essential for ensuring all occupied regions within a home are kept healthy.

Indoor pollutants rapidly change minute-by-minute and from one room to another within a home as occupancy, occupant activity, and wind-driven infiltration vary. For example, one person in a typical bedroom without ventilation increases carbon dioxide from 400ppm (outside air) to the threshold of bad air quality (1000ppm of carbon dioxide) in less than 40 minutes! Light exercise or increased mental stress will cut the time in half. Moderate exercise or physical activity such as cleaning will cut the time in half again. A person’s carbon dioxide and VOC (Volatile Organic Compound) pollutant output varies by a factor of ten from sleeping to vigorous physical activity.

It is a myth that “leaky” homes have good air quality. Air quality in a leaky home blows with the wind. Excess air, outdoor pollutants, and particulates blow into a leaky home during windy days while calm days have insufficient air flow and poor indoor air quality. .. read more at Build Equinox

Passive House - the basics

For those wanting to understand the 'passive house' performance standard here is a really good primer from the Passive House Alliance

Passive House Principles

Passive building comprises a set of design principles used to attain a quantifiable and rigorous level of energy efficiency within a specific quantifiable comfort level. "Optimize your gains and losses" based on climate summarizes the approach. To that end, a passive building is designed and built in accordance with these five building-science principles: 

• Employs continuous insulation throughout its entire envelope without any thermal bridging.
• The building envelope is extremely airtight, preventing infiltration of outside air and loss of conditioned air.
• Employs high-performance windows (double or triple-paned windows depending on climate and building type) and doors - solar gain is managed to exploit the sun's energy for heating purposes in the heating season and to minimize overheating during the cooling season.
• Uses some form of balanced heat- and moisture-recovery ventilation.
• Uses a minimal space conditioning system. 

Passive building principles can be applied to all building typologies – from single-family homes to multifamily apartment buildings, offices, and skyscrapers. 

Passive design strategy carefully models and balances a comprehensive set of factors including heat emissions from appliances and occupants to keep the building at comfortable and consistent indoor temperatures throughout the heating and cooling seasons. As a result, passive buildings offer tremendous long-term benefits in addition to energy efficiency: 

• Superinsulation and airtight construction provide unmatched comfort even in extreme weather conditions.
• Continuous mechanical ventilation of fresh filtered air provides superb indoor air quality. 
• A comprehensive systems approach to modelling, design, and construction produces extremely resilient buildings. 
• Passive building principles offer the best path to Net Zero and Net Positive buildings by minimizing the load that renewables are required to provide. 

The Performance Standard

North American building scientists and builders with funding from the U.S. Department of Energy (DOE) and the Canadian government were the first to pioneer passive building principles in the 1970s. In the late 1980s the German Passivhaus Institut (PHI) built on that research and those principles and developed a quantifiable performance standard that continues to work well in the Central European and similar climate zones.

However in practice, the PHIUS Technical Committee, PHAUS members, and project teams building projects in North America learned that a single standard for all North American climate zones is unworkable. In some climates, meeting the standard is cost prohibitive, in other milder zones it's possible to hit the European standard while leaving substantial cost-effective energy savings unrealized.

 

As such, in cooperation with Building Science Corporation under a U.S. DOE Building America Grant, the PHIUS Technical Committee developed passive building standards that account for the broad range of climate conditions, market conditions, and other variables in North American climate zones. The result is the PHIUS+ 2015 Passive Building Standard – North America, which was released in March of 2015. Regardless of the metric, the principles are the same, and the passive building community is working hard to make this approach the mainstream best practice for building design and construction.

Why not act now

This gets us way beyond feel-good tokenism and lasts for multiple generations.

Ann Kovalic said it well in her essay Passive-Aggressive Haus  ( a great read!)

“There’s no good reason,” I used to say, “why we don’t build more Passive Houses in this country.” I assumed it was just Canadian denial of our climate; we like to wear thin jackets and complain about the weather. Are we this way with our permanent shelters too?
There are indeed no good reasons. But there are reasons.

Adopting the Passive House building technology and standard may be one of the easiest and least costly ways to greatly reduce carbon emissions around the world. The reduction of emissions would result from a reduction in energy demand as opposed to the conversion to a different energy source. This is significant because a reduction in total global energy demand, as opposed to only a conversion to a renewable energy source, is necessary to reduce emissions to acceptable levels.

Furthermore, unlike many other methods to address climate change and reduce emissions, this technology is not years away. It exists now and is being used in all regions in the U.S. (as well as in Canada, Europe Japan and China) and with all major building types.

Also, the adoption of this technology doesn’t require a shift in the public’s beliefs about climate change or appreciation of it as a danger. This makes it possible to sidestep politically contentious arguments about the environment when discussing the technology.

Erase40.org

Its a brave new world and you need a guide

Navigating the process of designing and building a high-performance home demands attention to detail at every stage from concept to completion. A knowledgable, qualified, compatible guide and mentor for the journey is invaluable. We found ours in Rob Blakeney at Local Impact Design.

Rob is a professional engineer in Guelph with a personal passion for passive house, with the training and the experience to provide guidance, modelling, design and oversight to see us onto the right course. @LocalImpactDsgn