> For the complete documentation index, see [llms.txt](https://docs.cscale.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs.

# Structure

Lower structural embodied carbon in C.Scale: compare mass timber, steel and concrete systems, set low carbon concrete, or work in Detailed Design.

## Simple Design

#### **Existing to Remain**

The reuse of a pre-existing structural system for a given percentage of the building's floor area. Note that these measures only affect upfront emissions; refurbishments are counted normally.

#### Primary Structural System

Specification of a structural system other than the system modeled in the baseline. Note that this is not strictly a carbon reduction measure, as the substitution of some structural systems with some others can lead to an increase in embodied emissions.

* **Reinforced Concrete**. A structural system comprised of columns, beams, and slabs of concrete reinforced with steel that provides tensile strength.
* **Mass Timber**. A structural system comprised of massive beams, panels, and columns, often assembled by aggregating many smaller timber elements. This approach assumes that timber elements are aggressively substituted for other structural materials.
* **Wood Frame**. A structural system comprised of dimensional lumber, plywood sheathing, and reinforced concrete cores and podiums.
* **Steel Frame**. A structural system comprised of steel columns, beams, and girders connected with rigid or pin joints. Floors are steel decking with a concrete topping slab.
* **Hybrid Concrete-Steel**. A structural system that combines rigid steel frames with concrete columns, beams, and slabs. These hybrid structures are more materially intensive and may be used when there are significant seismic loads, in high-rise buildings, or for programs with very high live or environmental loads.

#### Secondary Structural System

Specification of a secondary structural system, and its associated percentage of the overall building structure.

#### Structural Efficiency

Specification of the the structural material intensity based on the chosen material. The selections made in this field sample the distribution of bills of materials (not carbon intensities). The underlying data is listed in [C.Scale's whole life carbon methodology](https://docs.cscale.io/the-c.scale-tm-data-model/embodied-carbon).

#### Live Load

The design live load, in psf or kPa, used to estimate structural quantities. C.Scale fills in a default you can override.

#### Concrete Carbon Intensity

The specification of concrete for a given strength class. Concrete emissions are assessed regionally. See [Structure](https://docs.cscale.io/the-c-scale-tm-data-model/whole-life-carbon/structure.md) in the C.Scale data model for details on how carbon intensity data is regionalized.

> **Responsibly-sourced timber.** C.Scale counts carbon storage for all timber whenever D2 is in the project's scope. Only claim it if the wood is responsibly sourced. C.Scale recommends meeting at least two of three criteria (traceable supply chain, growing forest carbon stock, and certified/recycled/reclaimed material). See [Stored Carbon](https://docs.cscale.io/the-c-scale-tm-data-model/whole-life-carbon/stored-avoided-carbon.md) in the C.Scale data model for full criteria and methodology, or refer to procurement guidance from the [Climate Smart Wood Group](https://www.climatesmartwood.net/procurement/).

## Detailed Design

The Detailed Design configurator supports the input of project-specific data.

To begin using this feature, turn on **Detailed Design** within the Structure accordion, and then click "**Configure Structure**".

![Turn on "Detailed Design".](https://docs.cscale.io/images/cscale-ui-structure-detailed-design-toggle.png)

![Structure Detailed Design Configurator.](https://docs.cscale.io/images/cscale-ui-structure-detailed-design-configurator.png)

You can configure structural materials using the table and the following fields in the right-hand panel:

#### Section and Subsection

The structural section (substructure or superstructure) and subsection where the material is applied.

#### Quantity

The quantity of material.

#### Material

The material used in the structural design.

#### Material Origin

The source of the material.

#### Service Life

Number of years over which at least half of the material will be replaced.