Life cycle energy and costs of sprawling and compact neighborhoods

Abstract

Purpose

The aim of this study is to compare the life cycle energy and costs derived from the production and occupation of social interest housing models located in two different types of neighborhoods: compact and sprawling. Two neighborhood development alternatives in Mexico City were established and evaluated including the potential impacts analysis of the built environment/infrastructure and the commuting of the occupants.

Methods

The study includes the conventional phases of a building life cycle (LC)—preoccupation, occupation, and post-occupation—but it was expanded to include a fourth phase, “occupant transportation,” to cover the commuting potential impacts. The methodology consists of four main stages: (1) definition of function, functional unit, and scope; (2) data collection—divided in three main steps: architectural, land costs and transformations, and commuting data; (3) impact assessment—we used software SimaPro v8.0.1 to manage the LC inventory data; and (4) interpretation of results and sensitivity analysis.

Results and discussion

In the preoccupation phase, the sprawling neighborhood cell (NC) cumulative energy demand (CED) is 30 % larger than the compact NC ones. Regarding the LC costs, land costs strongly impact the compact NC, but when aggregated in the preoccupation phase, the LC costs for the sprawling NC are only 14 % above those of the compact NC. For the occupation phase, results show that the compact NC has lower CED (by 10 %) and LC costs (16 %) than the sprawling NC. The occupant transportation phase plays a highly important role, since it represents up to 28 % of total LC CED and up to 54 % of total LC costs. This phase affects significantly the sprawling NC, which has a 25 % higher CED and doubles LC costs, when compared with the compact NC. Post-occupation phase contributes just in a small proportion of the total CED and LC costs for both NC, since it accounts for 3 % or less of the total energy and LC costs. Overall results show that the compact NC has lower CED and LC costs than the sprawling NC.

Conclusions

The results show that occupant transportation phase plays a highly important role in the neighborhood performance. Neighborhood development assessment should consider a number of variables beyond CED and costs. However, in order to improve the sector’s energy efficiency and household’s economy, we recommend to consider house location as it can be as important as other energy or cost-reduction actions in neighborhood development.