CA22 - Carbon Calculator
The CARE Tool is a game-changer for calculating carbon at the beginning of your project.
THE TOPIC - CARBON RETROFITS
If you’ve been paying attention to the world of carbon, then you’ve probably heard the importance of building reuse, retrofit, and adaption. A few days ago I wrote a short piece about it on LinkedIn, and it got some great feedback.
The difficult place to be as an architect is ranking the importance of different strategies, especially early in the design process. Here are some of the typical questions that might go through your mind:
Is it better to renovate and reuse or tear down and start over?
The existing building doesn’t perform well, will that outweigh the benefit of keeping the it?
How do I know how much carbon is really being saved?
Isn’t a high-performing building better in the long run than a poor performing one?
These are all valid questions that we often ask ourselves. The problem is that typically without a lot of work, these questions are nearly impossible to answer.
ENTER THE CARE TOOL | Carbon Avoided: Retrofit Estimator
“The CARE Tool allows users to compare the total carbon impacts of renovating an existing building vs. replacing it with a new one”
The Care Tool is for exactly that. Providing early-stage carbon comparisons between existing, renovated, and new buildings. Let’s take a quick dive-in so you can see what it’s about!
Before we get further into today’s topic I wanted to hear from you!
Step 1 - General Information
Input basic project information (unfortunately USA projects only right now). When it comes to climate information and the electricity grid you have a choice - default or manual input. Let’s go with default for this test.
Washington State - Blaine (Northern Washington)
Climate info - default
Electricity Grid - default
Step 2 - Existing Building
Input the size and type of the existing building. For this test we are going to look at the following:
10-Story Office Building with Ground level Restaurant
250,000 SF Total Floor Area
3 Levels of underground parking
Steel + Concrete Construction
55% Window to Wall Ratio
EUI of 343.2 kWh/m2 (108.8 kBtu/ft2)
Existing Operational Emissions Intensity = 12.2 kgCO2e/ft2
Existing Embodied Carbon Intensity = 0 kgCO2e/ft2
Step 3 - Reuse Scenario
Input the planned conversion scenario. Here you can specifcy the anticipated reuse of each component such as envelope, structural system, MEP, and others. For this test we are going to look at the following:
Converting office tower to multifamily residential
Reusing 60% of the structural system
Major envelope replacement
Replace all MEP systems
Reuse Operational Emissions Intensity = 5.6 kgCO2e/ft2
Reuse Embodied Emissions Intensity = 24.9 kgCO2e/ft2
Step 5 - New Building
This is really the main comparison most people need to understand more fully. Input values for a new building. For this test we looked at:
10 Story multifamily with restaurant on ground level
50% target energy reduction - EUI of 87.4 kWh/m2 (27.7 kBtu/sf)
Not all-electric system
New Building Operational Emissions Intensity = 2.8 kgCO2e/ft2
New Building Embodied Emissions Intensity = 46.5 kgCO2e/ft2
The Results
The results are clear and simple to understand. At about 5 years the carbon outputs cross each other. The interesting part in this scenario is that over a 30-year timeline a new building has about 15,000 Tons less total carbon.
It’s great to see both embodied and operational carbon alongside each other for easy comparison which typically isn’t the case. We often get caught looking at one or the other and need to consider both.
PS - The importance of looking at more than just carbon. This isn’t meant to tell you which option is best, it’s only intended to look at the carbon impact of both options. Think about the garbage, the construction logistics, the impact on the neighbourhood, the quality of the architecture, the damage to the ecosystems, the overall cost. Carbon is important, but it’s one piece of a very complex puzzle.