Walkability/New construction: Difference between revisions

Latest revision as of 14:27, 5 November 2023

If walkability is achieved by building brand-new neighborhoods, how long would it take to "break even" considering the carbon emissions of the construction & materials?

Simplified model

consider the carbon footprint of making a new building, per person living there.
assume a full extreme lifestyle change: people go from "USA average" amount of driving, to zero driving.

In such a case, it would take about 7-8 years to pay itself off:

(see maths)(see maths)

building.construction_ghg_by_floor_area

530.43 kg/m^2

CO2 emissions involved in making a building, per unit of floor area

Includes all materials and construction processes.
But probably doesn't include furnishings.

Source:
Case Study on Carbon Footprint Life-Cycle Assessment for Construction Delivery Stage in China
by Xiaojuan Li, Chen Wang, Mukhtar A. Kassem, Shu-Yi Wu, and Tai-Bing Wei
https://www.mdpi.com/2071-1050/14/9/5180
Sustainability 2022, 14(9), 5180; https://doi.org/10.3390/su14095180

Quote: "...the area carbon-emission intensity is between 400 and 800 kgCO2/m^2, and the average area carbon emission of the building is 647.99 kgCO2/m^2 compared to other research results for emissions around 412.87 kgCO2/m^2"

So I decided to take the midpoint between both figures.

gasoline.ghg_by_energy

71.30 kg / million btu

CO2 emissions of burning gasoline

https://www.eia.gov/environment/emissions/co2_vol_mass.php

average_us_vehicle.fuel_usage

489 gallons gasoline/year

The average American vehicle uses this much gasoline (measured in energy units)

Top Numbers Driving America's Gasoline Demand
https://www.api.org/news-policy-and-issues/blog/2022/05/26/top-numbers-driving-americas-gasoline-demand

Note: Since the statistic is mentioned specifically in relation to gasoline, we can '''probably''' assume that it excludes diesel-powered vehicles such as semi trucks. But the website doesn't specify that, so it's anyone's guess.

usa.registered_vehicles

275.9 million

Number of registered vehicles in the USA

Top Numbers Driving America's Gasoline Demand
https://www.api.org/news-policy-and-issues/blog/2022/05/26/top-numbers-driving-americas-gasoline-demand

usa.population

334416477 people

Number of people living in the USA

United States Population (Live) - Worldometer
www.worldometers.info › world-population › us-population
Last updated April 7 2022

home_space

400 square(feet) per person

private_fraction_of_building

70%

Percent of the building's floorspace that is private living space

The rest is hallways, stairwells, and common rooms.

(calculation loading)

The real-life figure might be higher, because...

can't really expect a full change to zero driving, just a lot less than before
the calculation didn't include interior furnishings of the building, as far as I know

The real-life figure might be lower, because...

the footprint of heating the new place(...)( i.e. an apartment or condo in a multi-unit residential building ) would probably be lower than the old place(...)( i.e. a single-detached suburban home )
less construction in other ways (especially road maintenance)

In any case, the carbon payoff of new construction could be worth it if there's no better option for Walkability/Existing housing.

@@ Line 1: / Line 1: @@
+If [[walkability]] is achieved by building brand-new neighborhoods, how long would it take to "break even" considering the carbon emissions of the construction & materials?
+==Simplified model==
+* consider the carbon footprint of making a new building, per person living there.
+* assume a full extreme lifestyle change: people go from "USA average" amount of driving, to zero driving.
+In such a case, it would take about 7-8 years to pay itself off:
+<tab name="(see maths)">
 {{dp
 |<nowiki>building.construction_ghg_by_floor_area</nowiki>
 |<nowiki>530.43 kg/m^2</nowiki>
 |<nowiki>CO2 emissions involved in making a building, per unit of floor area</nowiki>
-|<nowiki>Includes all materials and construction processes.</nowiki><br /><nowiki>
+|<nowiki>Includes all materials and construction processes.</nowiki><br /><small>But probably doesn't include furnishings.</small><br /><nowiki>
 </nowiki><br /><nowiki>
 Source:</nowiki><br /><nowiki>
@@ Line 47: / Line 54: @@
 {{dp
 |home_space
-|350 square(feet) per person
+|400 square(feet) per person
 }}
 {{dp
 |private_fraction_of_building
-|65%
+|70%
 |Percent of the building's floorspace that is private living space
 |The rest is hallways, stairwells, and common rooms.
@@ Line 59: / Line 66: @@
 |years (average_us_vehicle.fuel_usage * gasoline.ghg_by_energy * usa.registered_vehicles / usa.population)
 }}
+</tab>
+The real-life figure might be higher, because...
+* can't really expect a full change to ''zero'' driving, just a lot less than before
+* the calculation didn't include interior furnishings of the building, as far as I know
+The real-life figure might be lower, because...
+* the footprint of heating the new place{{x|i.e. an apartment or condo in a multi-unit residential building}} would probably be lower than the old place{{x|i.e. a single-detached suburban home}}
+* less construction in other ways (especially road maintenance)
+In any case, the carbon payoff of new construction could be worth it if there's no better option for [[Walkability/Existing housing]].
-<!-- TALK: i should try to find a different case study that deals with per capita (or total emissions and total number of residents) instead of guesstimating floor space per person -->
+<!-- TALK: should i try to find a different case study that deals with per capita (or total emissions and total number of residents) instead of guesstimating floor space per person -->