Published on September 26th, 2019 | by Michael Barnard0
#EC2019 Part 3: Is Building Energy Efficiency Overrated?
September 26th, 2019 by Michael Barnard
The day of the Global Climate Strike, September 20th, I participated in a fascinating all day conference in Vancouver, British Columbia. It’s the fourth annual conference put on by the BC Sustainable Energy Association. There are three or four threads I want to pull at, but this one is focused on the segment on building energy efficiency.
Other articles have dealt with the excellent transportation portion of Vancouver’s Climate Emergency Response plan and persistence of fossil fuel lobbyists. I intend at least one more related to the larger question of BC being small green province in an increasingly dark gray sea.
The portion of the agenda focused on building efficiency was interesting, and raised as many questions as it answered. While the presentation by Matthieu Loos of Powertech Labs Inc. was useful in helping many realize that we didn’t have an electric car charging power supply problem, but rather a charging time and rate management problem, that’s not the element I want to focus on.
Instead, I want to look at the paired presentations by Amir Ekhlasi, a professional home energy advisor, and by Farshid Borjian, a structural engineer speaking in his capacity as Executive Director of the Masonry Institute of BC. Ekhlasi’s focus was on the steps of the BC Building Code Step Guide, which came into effect in 2018.
There are three or four things to call out with this guide. First, BC is reasonably making the lower steps mandatory over the next few years and leaving the higher levels to incentives programs. The second is that there is an associated set of material for multi-unit buildings which I’ll explore briefly later in the article.
But the biggest question that this raised in my mind is how meaningful this step guide actually is. These are statements of energy efficiency, not carbon load of the building. And while reducing energy use is good, what’s even better for carbon emissions is to decarbonize energy and decarbonize materials. Vancouver is leading the way on this with its Climate Emergency plan:
4. Zero emission space and water heating – By 2025, all new and replacement heating and hot water systems will be zero emissions.
This is paired with the accelerated action: “Make it more affordable and easier to get a permit for heat pumps.” And in the accelerated actions related to restaurants and breweries, they mention both renewable natural gas and induction stoves, both means to arrive at much lower emissions. This should, in my opinion, be extended to gas ranges in homes and multi-unit dwellings as well, with only induction ranges allowed in new construction and retrofits.
That means no more natural gas furnaces or hot water heaters will be installed in new construction or allowed to be replaced with more natural gas appliances in older construction. What natural gas ranges aren’t replaced with induction ranges, the much preferable path, would be powered with renewable natural gas. When all energy flows into a building are electricity or very-low carbon renewable natural gas, how important is the efficiency of use of energy in the building?
As Vancouver author William Gibson says “The future is already here. It’s just unevenly distributed.” Right now, the future is Vancouver, and it needs to be distributed to the rest of BC.
This calls into question the value of net-zero building construction as well. Most of British Columbia’s population lives in the part with poor solar resources and higher-density buildings. Trying to generate significant electricity on site requires decent solar resources and sufficient unshaded, correctly-angled roof space to mount solar panels commensurate with the consumption within the building, neither of which are in large supply where the majority of people live.
Analyses suggest $320 per ton of CO2e for residential solar. Lazard’s LCOE analysis provides a range of $160–$267 per MWh for rooftop. The costs per ton make it clear, especially for BC’s circumstances, that there is little merit in net-zero home requirements or incentives, and there is more merit for decarbonizing grid electricity and eliminating natural gas use.
Net-zero is, in my opinion, a sprawl architecture target, not a reasonable choice compared to urban densification, another of the City of Vancouver’s targets. I suspect it will be diminished in priority over the years, and was pleased to see that it wasn’t a requirement yet. However, the incentive program for net-zero buildings should probably be reconsidered. It’s a low-value wedge diverting attention and resources from high-value efforts.
That all said, there is a value proposition in at least up to Step 3, which is that as new buildings come onto the energy flows, the efficiencies mean that they don’t increase demand as substantially. While natural gas used to diminish this impact by diverting one energy use to a high-carbon on-premise model, that’s not available in the future. As such, higher efficiency buildings will all use carbon-neutral electricity to go further.
But that brings us to the next question. If all of the energy flowing into a building is low-carbon, what about its embodied carbon in the materials and construction process?
There’s an important call-out on this: “Wood-frame.” BC has adopted guidance for buildings up to six stories tall that they be wood-framed, not concrete construction. As the production of Portland Cement is responsible for up to 8% of the world global greenhouse gas emissions, it’s eminently sensible to avoid its use as much as possible. The six-story height is an important note as well. While we think of Vancouver’s high-rises as dense, urban living — and they are — the center of Paris exceed Vancouver’s density quite substantially, with 21,616 per square kilometer compared to 5,400. Paris, until recently, only allowed buildings up to 9 stories tall, and most were six stories at most. Outside of Vancouver’s core, densification with six-story buildings makes a tremendous amount of sense.
Here’s where Farshid Borjian of the Masonry Institute of BC’s presentation comes into the question. He mentioned the six-story wood-frame element in passing, saying that his organization had lobbied unsuccessfully for four stories maximum. Very reasonable, and he was clear throughout that he was a concrete advocate. His presentation focused on thermal density of building materials, something critical to efficient building heating and cooling. Concrete, when used properly, does have excellent thermal density properties and does make energy use more efficient.
But if all the energy is low-carbon, then the embodied carbon in the building materials becomes the dominant factor in overall emissions. According to a Building Green report, as this shifts, 90% of emissions of new buildings will be from the embodied concrete. And according to research out of China on residential construction materials, concrete has roughly 7 times more embodied carbon than wood. All of this is to say that the Masonry Institute focus on thermal density is misplaced in the larger picture, and Borjian was more than gracious in saying that given the industry he represented, that his focus was on concrete.
BC’s approach to this is excellent so far, with a push for more wood construction which is much lower carbon, and increased height of wood-framed buildings. The net-zero incentives are misplaced here as well, in my opinion, however, that’s a nit.
But there’s more good news in this space from BC. The current government is shifting the limit on wood-framed construction up to 12 stories. This is a place where BC is leading Canada, which is going to introduce the changes federally in 2020.
Back to concrete. Vancouver is, famously, a city of glass towers. And those towers are more than 12 stories tall.
And they require concrete. Decarbonizing concrete is still a much needed effort. As stated, about 8% of CO2 emissions globally are from concrete. This is due to the limestone calcination process that makes quick lime, a key ingredient in cement. About 40% of that is from the energy required to bake the limestone, and 60% is from CO2 emitted by the limestone as the carbon content combines with oxygen from the atmosphere.
The Masonry Institute of BC is downstream from the cement manufacturing process, so Borjian didn’t have insight into the efforts to decarbonize concrete beyond the reuse of salvaged concrete aggregate. That will entail both decarbonizing the high-energy requirements and capturing the CO2 emitted by the process and doing something with it. That’s a non-trivial task, but if BC were to start setting embodied carbon limits on concrete used within its borders, it might provide an impetus.
To try to pull this together, while efficient buildings are good, there are limits to how much should be invested in energy efficiency programs compared to decarbonizing electricity, electrifying everything and ensuring buildings are built with low-carbon materials. BC and Vancouver have an imperfect but still good balance on this, with Vancouver leading BC. If the rest of the world adopted simply BC’s standards, this would be a major global wedge by itself, but inadequate for the 1.5 degrees efforts needed by 2030, something Vancouver’s additional efforts are more in line with.
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