---
title: "Deconstruction Wood Density Sensitivity Analysis"
subtitle: "Using average density from OSU salvage wood study Table 2"
author:
- Andey Nunes, MS
- Research Analyst 2
- Oregon DEQ
date: "`r format(Sys.time(), '%B %d, %Y')`"
output:
   html_document:
    df_print: paged
    toc: yes
    toc_depth: '3'
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)

packages <- c("knitr", "tidyverse")
lapply(packages, require, character.only = T)
options(digits = 3)
options(scipen = 999)
```

# Introduction

In order to understand the effects of changing density facotrs for softwood lumber, this sensitivity analysis uses the same project data from the original Deconstruction data analysis and substitutes values from an Oregon State University study of salvaged wood samples from local Deconstruction projects.

The original report used the softwood lumber density value of 433.57 kilograms per cubic meter from the American Wood Council's Softwood Lumber Environmental Product Declaration. The values from the OSU study range from a minimum 338.13 to maximum 718.41 kilograms per cubic meter with an average denisty value of 530.70 kilograms per cubic meter.

This summary report first compares the findings from the original report to the results of executing the entire analysis using the OSU average density value. Time permitting, the same analysis over the range of density values may also be included.

# Comparison to average OSU density factor

**Average density value**

> 530.70 kg/m^3^

## Overall house weights
Since dropbox weights were derived directly from the reciepts, these values do not change. Only calculated estimates of weight for salvage wood items will increase when using the new average density value. 

For the **average house**, the softwood lumber salvage value increased from 7559 pounds to 9243 pounds, which brings the total average salvage material weight to 10,587 pounds, which is an increase of `r 10587-8902` pounds. This increase is reflected by an increase in the average percent salvage from 23.6% to 26.9%.

## Carbon impacts

The effect of increasing the wood density showed a greater benefit for deconstruction from a carbon perspecive. The total global warming potential impact for the average house by `r 13849-12445` kgCO2e for deconstruction, while the demolition benefit increased by `r 6170 - 6009` kgCO2e. This translates into an increase in the average difference between deconstruction and demolition scenarios from 5.47 to 6.53 kgCO2e on a per square foot basis. 

## Energy impacts

The effect of increasing the wood density is an increase in energy savings in the demolition scenario over the deconstruction scenario. Average house deconstruction energy benefits increased by `r 88994-85938` MJ while the demolition scenario benefits increased by `r 115266 - 106726` MJ. This translates into an increase of `r 22.33 - 17.67` in the per square foot difference between demolition and deconstruction.

# Comparison to maximum density value



