LEED Baseline Strategies

Strategies for creating the baseline in One Click LCA

When creating your baseline building for the purpose of completing a LEED certification, there are a few strategies you can use to create the baseline. The proposed design and the baseline building must have the same:

• Size (Gross floor area)
• Programmatic function
• Orientation
• Location
• Energy performance

We have detailed four baseline strategies below that you can use.

Option 1 - Using the proposed building analysis

With this strategy you are creating design variants and the baseline based on current proposed building analysis for the baseline.

For the majority of projects this is the most efficient baseline strategy. In this strategy, you will first calculate the life cycle assessment of the currently proposed building design and then use that one to study alternative material / structural options which may or may not lead to changing the proposed building. Finally, the baseline can be one of the created alternatives.

The benefits of this strategy are that as the baseline is based on the proposed building design you’ll be easily able to ensure the equivalency in floor area, location, function, energy performance, and directional exposure. When testing different material / structural choices you’ll just have to ensure that:

• All alternative enclosure roof, wall and slab materials are modelled with similar R-value / U-value / F-Factor to ensure similar energy loss through the structure.
• The size and location of the windows and skylights were kept similar in both models to ensure similar energy loss through the structure.
• Structural elements were modelled with the required load-bearing capacity

Steps to complete the analysis:

1. Create a copy of your existing design by clicking its name and choosing ”Copy”. You can also rename a design from the same dropdown menu using the “Modify” option.

2. Open the design and consider alternatives. Open the created design’s building materials query to study “what if” scenario analyses and support design decisions to evaluate and select environmentally preferable assemblies and materials. A good way to start is to check your existing design’s report to find out what causes a lot of emissions and to check if there are any more sustainable alternatives available. Examples of alternatives analyses could include the following:

• Choosing different types of materials (e.g. brick wall vs. concrete wall)
• Evaluating different structural system types, such as load-bearing walls versus columns
• Choosing products with different kind of service lives
• Choosing products from different manufacturers
• Optimizing structural system design (e.g. column spacing, slab depth)

3. Save the final proposed design.

4. Open the Results page of the proposed design. Click the 'Compare' button and select as the point of comparison the earlier building design. The percentage difference will appear to the table. You can create several different alternatives to find out options and to define the baseline.

Option 2 - Using an energy model

With this strategy you are using an energy model for the baseline. 

Your baseline model would be compliant with ASHRAE 90.1 appendix G (LEED v4: 2010 / LEED v4.1: 2016), and your quantity take off would come directly from the energy model. When creating your baseline / proposed building you will have to ensure that:

• Both proposed and baseline building has the same floor area and directional exposure
• All alternative enclosure roof, wall and slab materials are modelled with similar R-value / U-value / F Factor to ensure similar energy loss through the structure. The energy model already provides you with the correct thickness for materials based on the respective R/U/F values which means the proposed building is accurate on the topic of energy performance. 
• The size and location of the windows and skylights were kept similar in both models to ensure similar energy loss through the structure
• Structural elements were modelled with a required load-bearing capacity

Steps to complete the analysis:

1. Create a copy of your existing design by clicking its name and choosing ”Copy”. You can also rename a design from the same dropdown menu using the “Modify” option.

2. Open the design and consider alternatives, keep in mind that the energy performance has to remain equivalent. If unsure, you can use e.g. an R-Value calculator to find out the equivalent R-Value performance for different types of materials.

3. Save the final designs.

4. Open the Results page of the proposed design. Click the 'Compare' button and select as the point of comparison the earlier building design. The percentage difference will appear to the table. You can create several different alternatives to find out options and to define the baseline.

Option 3 - Using early stage or alternative design models

With this strategy you using early-stage or alternative design models for the baseline. 

If you are able to start the process early in the design process or you have available information about some design options that were studied earlier you may use these as a baseline. In this case, you will need to calculate an LCA based on the information of the early stage/alternative design.

The benefits of the early model are that you may have a chance to suggest significant changes to the building design to improve it. In both the alternative and early-stage model you will also have the baseline information already available from your project so you do not have to figure out which kind of alternatives could be suitable. However, if the project design has changed a lot on the way you’ll have to pay some attention to checking the equivalence and may need to change the baseline to match the final design to ensure comparability. When creating your baseline / proposed building you’ll have to ensure that:

• Both proposed and baseline building has the same floor area and directional exposure
• All alternative enclosure roof, wall and slab materials are modelled with similar R-value / U-value / F Factor to ensure similar energy loss through the structure
• The size and location of the windows and skylights were kept similar in both models to ensure similar energy loss through the structure
• Structural elements were modelled with a required load-bearing capacity

Steps to complete the analysis:

Please note that this applies to a case where you start in the early stage with the current model or have the design data for alternative design easily available as BIM or excel export. In other cases, we recommend still creating the baseline based on the proposed building but using the material choices from the alternative or early design option for it.

1. Create a new design and name it 'Baseline'.

2. Fill in the information based on the design and study results. If you already have calculated the proposed building you can compare the results by pressing the 'Compare Designs' button in the result report page.

3. Optional: Create a copy of this design to study results by clicking the name and choosing 'Copy'. Open the created design’s construction materials query to study “what if” scenario analyses and support design decisions to evaluate and select environmentally preferable assemblies and materials. A good way to start is to check your existing design’s report to find out what causes a lot of emissions and to check if there are any more sustainable alternatives available.

Option 4 - Using a benchmark or archetype building

With this strategy you using an archetype or benchmark building for the baseline. 

If either of the previous options does not work for you it is also possible to create an archetype building with typical local structures for the baseline. This might be an easier way if you are planning to change the whole structural system of the project. Also, in this case, the easiest way is to use the geometry of the existing project to ensure the equivalence though you are allowed to choose the geometry too as long as the floor area, directional exposure and directions of windows remain the same. When creating your baseline / proposed building you’ll have to ensure that:

• They serve the same function and have the same location which for instance defines the needed foundation structures
• Both proposed and baseline building has the same floor area and directional exposure
• All alternative enclosure roof, wall and slab material are modelled with similar R-value / U-value / F Factor to ensure similar energy loss through the structure
• The size and location of the windows and skylights were kept similar in both models to ensure similar energy loss through the structure
• Structural elements were modelled with the required load-bearing capacity

The easiest way to do this is to use Carbon Designer, to use the average constructions from the database or defining the constructions you wish to use with our Private Constructions feature. 

Steps to complete the analysis:

1. Define the geometry for the baseline project, this means the areas for the included constructions such as external walls or roofs. If you do not use the same geometry with the proposed building ensure the same directional exposure and similar location of windows and other openings. 

2. Use those areas to populate the Carbon Designer parameters, fill in the areas to our excel template in Carbon Designer or input them directly to the software using ready-made default constructions. Ensure that the insulation level and resulting heat loss are equivalent and ensure you use the same requirements for load-bearing capacity. Make sure you add all the necessary building elements.

3. Compare your results with the proposed design.