Posted on Tue, 03/29/2016 - 07:10
Compared with current emissions, that would be equivalent to reducing emissions from single-detached homes in the province by about 35% by mid-century.
“Improvements in energy efficiency requirements for new and existing homes in Alberta provide an opportunity to significantly reduce Alberta’s carbon footprint,” the multidisciplinary student team says in its project, Residential Building Codes: Insulation, Heat Loss, and Greenhouse Gas Emissions.
Figure 1. The students who carried out the residential energy systems project described here did so in fall 2015 as part of a capstone project in the Scie529 course that is taught by CESAR Director David Layzell. Students Scheu, Jones and Sher are training to be civil engineers while Xiao is in the mechanical engineering program and Jenden is in the natural science program.
“It is possible to implement the majority of these measures without a significant paradigm shift in building practices” or huge increase in costs – apart from “deep” retrofits of houses, they say. “Through well-implemented government incentives, (the measures) could be quite appealing to homeowners.”
Most people tend to resist change and many look at energy savings as something that’s hard to do and improve upon, says team spokesperson James Jenden, a fourth-year student pursuing a degree in energy sciences in the Faculty of Science’s natural sciences program.
Jenden, who has worked as a house framer, says “one the things I wanted to do in this project was to see if it is possible to radically improve the energy efficiency of houses in Alberta without changing completely how they are built. The answer to that is: Yes, we actually can make a big difference in the emissions from this sector without a huge amount of work.”
There are a total of 1.39 million households in Alberta, of which 883,000 are single-detached homes which together account for 150 square kilometres of floor area (Figure 2). Space heating in single-detached homes currently accounts for about 6 million tonnes (Mt), the vast majority of this coming from natural gas furnaces. Without changes in building practices and human behaviour, GHG emissions from single-detached homes are expected to increase by more than 40 per cent, to 8.4 Mt annually, by 2060. However, to meet the 2⁰ C climate change commitments that Canada made in Paris, the residential housing sector needs to reduce emissions by 65% to 80% from where we are today (Figure 3).
The greatest absolute reductions of GHGs in the residential housing sector can be attained by improving the Alberta building code for newly built homes, and by retrofitting older homes, the team found. The most economic methods for increasing residential energy efficiency are requiring high-efficiency furnaces and installing air barriers in houses. “Both of these are inexpensive to implement, and would have a significant impact on Alberta’s residential GHG emissions,” says their project.
Team used scenario modelling analysis
To do their analysis, the students started with CESAR’s Business-As-Usual Low Oil Sands Growth scenario for Alberta (described here in CESAR’s Jan. 26, 2016 blog), and assumed no changes in home-building practices. They then evaluated and modelled, in an alternative scenario, four possible mechanisms to reduce residential GHG emissions against this business-as-usual scenario. These mechanisms were: 1) improved building codes; 2) a home retrofit program; 3) mandatory high-efficiency furnaces; and 4) incentivizing smaller homes. To model the alternative scenarios, including estimating the costs of implementing each mechanism, the team used reference parameters from a ‘typical’ Alberta house.
The students showed that if each mechanism was implemented according to the alternative scenario, GHG remissions could be reduced by up to 4.4 million tonnes annually by 2060 (Figure 3). The scenario’s parameters were: encourage average home size of 120 square metres; legislate 95-per-cent efficient furnaces; retrofit half of old homes to reduce heating load by 50 per cent; and build new homes to reduce heating load by 50 per cent.
The students noted that Alberta government’s climate change plan includes a carbon tax of $20 per tonne of CO2e in 2017, increasing to $30 per tonne in 2018. Their modelling scenarios, they say, “suggest that upwards of $200 million could be collected annually for reinvestment into home energy efficiency programs. These funds could be used to encourage retrofits, or even rebuild of older inefficient homes, in an effort to reduce Alberta’s carbon footprint.”
Justin Pockar, Energy & Environment Coordinator for the City of Calgary, served as the volunteer expert advisor guiding the team’s project. He says the students’ work is important as it allows for a deeper understanding of the costs and benefits to energy efficiency initiatives. It is challenging to take proposed improvements in energy efficiency and apply pragmatic solutions to enact them, he notes.
“For energy efficiency in residential buildings, this is particularly true, as aspects of quality control, affordability and constructability all affect possible solutions.
“The students did an excellent job of not only trying to quantify the benefits of energy efficiency measures in homes, but to understand the applications and limitations of those measures in light of the practical applications.”
Arriving at a host of options for enacting energy efficiency in residential homes is critical, because it’s highly unlikely that any one solution will be applicable to all buildings, Pockar adds. “The uniqueness of the individual buildings is part of the complexity that the students had to overcome.”
Course instructor and CESAR Director David Layzell says the students’ work shows the challenge that the residential sector faces in efforts to rapidly decrease GHG emissions. “The students pushed each of their four initiatives very hard in their scenario modelling. Even so, by 2060 the single family residential sector is only halfway to where it needs to be to meet the mid-century target for limiting climate change to 2⁰ C,” he says. “While we should move in the direction the students have proposed, there will need to be more changes in this sector to meet climate change commitments.”
For example, Layzell notes: “Increasing the proportion of people living in apartments or attached housing rather than single-detached housing would further decrease energy use, because those types of housing are typically more energy efficient than single-detached homes.”
“Ultimately, residential space and water heating should probably shift to electricity, but only if the province has a grid that has a much lower carbon intensity than it does today.”
Four mechanisms for reducing GHGs
Canadian homeowners have the third-highest per capita energy use in the world, and Canada lags behind most European countries when it comes to residential energy efficiency. Alberta, for the residential housing sector, utilizes the energy efficiency requirements for housing and small buildings under section 9.36 of the 2014 Alberta Building Code, which comes into force on May 1, 2016, with a transition period ending November 2, 2016. The province has the authority to implement stricter building codes (including national codes) and, if desired, can finance retrofit programs and legislate furnace requirements and the size of new homes.
For new home builds, the students’ project suggests updating the building code in Alberta to require insulation values similar to the ones calculated in their energy-efficient reference home. This includes spray foam in the outer walls, triple-pane, Argon-insulated windows, and an air barrier – all readily available technologies.
However, one limitation of adopting a higher-standard building code is that it takes a long time to reduce cumulative GHG emissions, because of the slow turnover in housing stock. Significant reductions in GHGs aren’t realized until a sizeable portion of the housing stock is built based on the new standard. The students found that by 2050, only 50 per cent of Alberta’s housing stock would be built based on a new standard implemented in 2017. Nevertheless, their scenario modelling showed that by 2060, total GHG emissions from homes built to the new standard would be reduced by 52.9 million tonnes.
For energy efficiency home retrofits, the government could revitalize the retrofit program that was run in the mid-2000s, offering tax incentives to homeowners, the students suggested. They cautioned that retrofits are capital-intensive, and people without a significant amount of disposable income can’t typically afford to do them. Their calculations showed a “medium” retrofit, to reduce space heating by 35 per cent, could cost more than $63,000 per home. A “deep” retrofit, to reduce space heating by 50 per cent, could cost more than $87,000 per home.
“Despite these limitations, the only way to reduce emissions from the majority of the housing stock between now and 2060 is through a retrofit program,” they say. In comparison with retrofits, new homes built to achieve the 50-per-cent reduction in space heating would cost only an additional $34,000 per home. “It is therefore far more economical to reduce emissions via new homes than a deep retrofit program.” They found that retrofits could reduce GHG emissions by 27.6 million tonnes by 2060. A program offering government loans for retrofits could make them more affordable to a wider range of people, they suggested.
In February, Alberta’s NDP government, in its budget for 2015-16, announced a plan to invest $5 million annually in ‘green’ loans to Albertans, which would be used to make energy efficient retrofits to homes and businesses, such as upgrading windows and doors or installing solar panels and new furnaces. However, the program is not yet available. “Designing Alberta’s first comprehensive energy efficiency program under our climate leadership plan will take time to get right,” John Archer, an official with Alberta Environment and Parks, said in an email. “Work on an efficiency program is underway and will continue in the months leading up to the phase in of the economy-wide price of carbon [starting at $20 per tonne] beginning in 2017.”
High-efficiency furnaces most economical
Mandating furnace efficiencies is the most economic technology method for improving residential energy efficiency, the students found. A 95-per-cent efficient furnace costs approximately $3,000 more than a conventional furnace that’s about 80-per-cent efficient. Based on the currently projected price of natural gas and a home lifespan of 20 to 30 years, the carbon tax required to pay for the furnace upgrade is about $10 per tonne of CO2e, they calculated. This increases to a carbon tax of $40 per tonne for a 98-per-cent efficient furnace, which can cost up to $5,000 more than a conventional furnace. “Therefore, even if the price of carbon does not rise above $30 per tonne, a 95-per-cent efficient furnace is still a profit-earning change,” they say. Their modelling showed that 30 million tonnes of GHG emissions could be reduced by 2060 simply by increasing furnace efficiencies, if the conversion occurs over 10 years.
The obvious policy implication, the students note, “is that the government should establish guidelines on minimum Average Fuel Utilization Efficiency, and they should do so quickly. To ease the transition, the government could use some of the revenue from Alberta’s new carbon tax to ease the financial burden on homeowners.”
One reason why energy used for space heating – and the resulting greenhouse gas emissions – are increasing in Alberta is that homes built between 2000 and 2010 are approximately 37 per cent larger than those built from 1960 to 1980, the students found. A potential way to encourage homeowners into smaller homes is by instituting a tiered tax system, they suggested. Houses that are 120 square metres would have no taxes associated with them, while houses smaller than that could receive tax incentives and those larger than 120 square metres would have to pay a tax that rose exponentially with increasing house size. “If designed properly, this program could be tax neutral, or even serve as a source of revenue for other programs,” they say. The team’s analysis showed that reducing the size of the average single-detached home – which would cost nothing – could by itself reduce GHG emissions by 12.2 million tonnes by 2060.
Jenden says the team also looked at energy-efficient residential building practices used in Europe, such as ensuring houses face to the south on lots, putting most of the windows on the south wall, using passive solar heating design to augment space heating and other techniques. However, it is difficult in Canada to legislate, through building codes, a high energy-efficiency building style, the team discovered. Using a European-style approach to home building would be expected to further improve energy efficiency in and reduce greenhouse gas emissions in the residential housing sector, but Canadian laws don’t require it.
The team produced a scientific poster as well as a report on the project detailing their methodology, reference parameters and assumptions used in their modelling, and also providing a costing model and suggestions for government policies. They note that determining costs and prices was challenging, as there are many different kinds of houses and estimates per house can vary significantly. “For this reason, the prices and values calculated are subjective. This research provides the basis for the conclusions [in the report], but is not directly applicable to individual buildings.”
CESAR, established in 2013, is an initiative to encourage and communicate research and critical analysis around the choices involved in transforming Canada’s energy systems. CESAR builds data resources and visualization tools, analyzes past energy systems and models energy futures, to inform policy and investment decisions on transforming Canada’s energy systems toward sustainability.
Note: the homepage image pictures a detailed thermal infrared (TIR) heat-loss map showing space-heat escaping (red–hot, blue-cool) from individual buildings at a 50cm spatial resolution and 5/100 deg.C temperature resolution. Shot over the town of Okotoks, Alberta (Oct, 2015), this image is part of the 2016 MyHEAT Energy Efficiency Program Launch and was graciously provided by MyHEAT (© MyHEAT 2016).