May 25, 2018

Study Says More Density in Single Family Neighbourhoods is Greener

In Vancouver single family housing is demolished to make bigger new houses, often of the same style. Yet, in this study to be published in July by University of British Columbia researchers and MountainMath Software, the perception that new is greener and better is seriously challenged.
UBC Reports  notes that, “despite the better energy performance of the new homes, this cycle is likely to increase overall greenhouse gas emissions.” 
Even though the City of Vancouver has a Zero Emissions Building Plan which was supposed to eliminate emissions from new building by 2030, “the teardown cycle is preventing many single-family homes from surviving long enough to ‘pay back’ the initial impacts caused by construction materials, which are not accounted for in the current plan.”
The construction of new single family residences “will result in one to three million tonnes of added emissions between 2017-2050, even though the new homes will require less energy to heat and operate. It also reports that each percentage point increase in land value will result in an additional 130,000 tonnes of emissions in Vancouver during the same period.”
Jens Von Bergmann of MountainMath Software nails down the policy approach to alleviating this problem. While it will take 168 years for efficiency gains to recover construction impacts, this teardown cycle will cause emission to increase, “unless we change residential zoning to permit denser forms of housing.”
Higher density housing forms will last longer than the single family houses they replace and provide environmental benefits sooner. Study co-author Joseph Dahman observed that low to mid-rise housing, “increases overall housing stock, addresses affordability and creates a more vibrant public realm” .  
And thanks to this study, we know that density is greener too.
Images Vancouver Sun and Globe and Mail

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  1. Ah! I know and loved that first house so well! On 39th, just down from Highbury Street! Grew up walking by it. So unique.

  2. Not said in the report, but calculated independantly by both Jens and I, is that the payoff on a PassiveHouse is on the order 30 years, so far better than an ‘average’ building.
    If there’s an argument for replacing existing … its to go beyond code minimum, but then there were lots of good arguments for that before also (this just adds another good reason to push for PH).

  3. Misconception: New homes do not replace old homes in the same building style.
    The conclusion to be drawn from the first paragraph is that when it comes to redevelopment, new is not always greener or better. Full impact accounting will always indicate otherwise. Waste is always waste! Travel is always impactful.
    There is no evidence to suggest that the following statement is true: Higher density housing forms will last longer than the single family houses they replace.
    There is no evidence to suggest that the following statement is true: (that higher density housing forms) will provide environmental benefits sooner.

    1. I think “same building style” means single family detached replaced by single family detached.
      I agree that there’s no guarantee a higher density form will survive the wrecking ball any longer than a single family detached. I’ve seen plenty of multifamily buildings come down in the last few years and development proposal signs sit outside many others. There’s also no guarantee of increased density. In fact there are many situations where the replacement buildings are lower density than those they replaced. The same thing is happening in commercial real estate. Dozens of buildings from the 1970s and 80s are coming down including tall office and hotel towers.
      But on the quicker environmental payback surely it’s obvious that housing 4 families in a single structure is more efficient than doing so in 4 separate buildings. The payback in saved land, building materials, heating/cooling and transportation will offset construction much more quickly than replacing 4 old houses with 4 new houses.

  4. The study does not say that more density in single family neighbourhoods is greener. The study challenges the idea that newer is greener when replacing an older home with a newer home. The study highlights the environmental cost of tearing down older homes. A process called needless waste!

    1. `deleted as per editorial policy.
      here 4 storey building come with elevators, collective heatings (why bother to close that window when you will not see that your strata fee?)… this both easily offset all the saving you can do over a SFH…
      If you go to high rise, you constantly need to update to new safety code..virtually absolutely nothing go to the end of its life cycle…
      Personally I live in a SFH with 100 years single pane lovely windows – absolutely no intention to change that, but I know for sure that new windows are crappy and will not last more than 30 years and will not save that much energy if at all:
      when you compute the full life cycle of product (environmental impact to produce the material), yes don’t erase this old house !

      1. I live in a 110-year old house and we changed most of the larger, priority windows from single-glazed aluminum crap with the wind whistling in to reproduction fir with double glazing and storm windows with laminated glass (for sound attenuation as well as energy savings). Yes, it’s expensive, but was well worth it, and the icing on the cake was the restoration of the architectural character lost during the unfortunate spate of “modernization” during the Disco Decade. Yes, we could have gone vinyl, but that’s not the same and would arguably not last another century, as fir would with proper care.

  5. Also, greener in this context means environmental performance which is measured by the thermal performance of the building enclosure and the choice of energy supply, the efficiency of its utilization, and conservation practices in place. Density is not part of the green narrative.
    Densification always means more of everything and this is never a good thing for the biosphere. We can think of the mega city with it’s dense high rise inner core as a vast industrial factory in which we live out our daily lives amongst the clamor and choking gases of its workings. We call this environment a place of economic opportunity but we can see from a distance on a hot summer day a dome of haze over the City of Vancouver. The village with in its simplicity remains our best hope for the future.

    1. //Density is not part of the green narrative.//
      Note that populations grow – in order to house everybody here, we can either build up, or build out. Compact multifamily housing allows for more greenspace, more effective transit, and less car usage; how do clear cuts and suburban infill all the way to Hope help the environment?
      //The village with its simplicity remains our best hope for the future.//
      Perhaps you’d have a happier time if you moved to one? Anybody longing for the lumberjack boondocks that used to be Vancouver is going to be very, very disappointed.

  6. If we do not measure the environmental impacts of construction or the environmental impacts of urbanization operations, then we are fooling ourselves thinking that densification is a greening activity, when clearly in Vancouver it is not. We for example, never include the environmental costs of congestion which is a direct result of densification. Segregated land use planning has produced many transportation woes that could be solved by mixed use planning. Or we could for example establish new towns on best practices rather than always rebuilding, an approach which would be greener than our current strategy for housing an expanding population. Or we could see sprawl as an opportunity to establish new mixed use neighbourhoods, thus eliminating daily commuting needs………………..

    1. Sprawl is the cause of congestion, not the solution. Mixed-use planning inherently means more density and transit and less sprawl; that way, anything you can’t walk to can be reached fast by SkyTrain, meaning less of a need for driving and no congestion.
      “New towns?” Everyone wants to live in THIS town – nothing’s going to change that.
      And exactly how many forests will be logged, how many services and utilities built or brought to the middle of nowhere, in order to make these towns? How much greenhouse gas will be created by driving back and forth between these towns?
      If we’re going to talk about Soviet master planning in order to save the environment, let’s rip up every small town in BC and merge them into five or six cities. The plants and animals affected by habitat loss/fragmentation will thank us for it.

  7. I once came across a study by, I believe, the U of T Engineering School that compared energy consumption and GHG emissions between the urban and suburban parts of the GTA over time. In short, higher density areas — even with concrete towers — consumed less energy and emitted lower levels of GHGs on a per capita basis than the suburbs over the years. In addition, the higher energy consumption and emissions of higher densities during construction were completely offset by operating savings.

    Clearly, the link between transportation and housing plays out on a wider platform than affordability. The life cycle operating performance in these terms is also a crucial consideration when discussing urbanism.

  8. Windows … they’re installed so mindlessly. People hear ‘big picture window’ – sounds good – like ‘open concept kitchen’. Both are terrible.
    Look around. How many homes do you see whose big picture window is shuttered? Pretty much all of them. About the only time windows are not shuttered is when the place is for sale during an open house.
    So-called Energy Star windows have a dismal R-rating. Sure, they’re two to three times better than single pane, but compared to an insulated wall, that’s nothing.
    And it’s almost impossible to block light at night. Unfortunate, because the best sleep comes in blackout conditions. Our bedroom window has three layers of drapes and curtains – light still finds its way in.
    Likewise, sound penetration is a problem.
    Smaller windows which frame specific views are the best solution.
    I’m also a fan of exterior insulated shutters – electrically operated. That takes care of light, sound, heat, security, and hurricane conditions.
    And though the old-style double hung windows could be a challenge to keep operating properly, they facilitated the stack effect. Cross-ventilation sounds like it would work, but on hot summer days, there is often no wind.

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