Designing naturally-conditioned dwellings for warm and cold-temperate regions of Chile

A Lifecycle Assessment of a Low-Energy Mass-Timber Building and Mainstream Concrete Alternative in Central Chile

“…As seen in Figure 9 after the concrete foundations, the largest GWP share for the MT design was the cement mortar topping (6.3%) used to meet the fire and acoustic ratings of CLT slabs which can be substituted using multiple layers of gypsum, wood fiber, and/or stone wool boards [56]. Although a more significant effect will be seen on buildings with 6 stories or more where national fire ratings are more stringent [26], the GWP share of non-combustible gypsum and rock-fiber (1.2%) could be lowered by adding a charring layer to CLT and glulam [57]. For non-load-bearing walls where minimum fire ratings are 0.25-0.5 h [26], an interesting alternative would be replacing aluminum frame with 60 mm thick CLT partitions.…”

“…The development, which was designed for a solar decathlon contest held in 2019 in Santiago [25] by a Chilean architectural team of the TNC project, has six apartment blocks of 20 flats each, four large open courtyards, ground-floor facilities, and retail shops. Aiming to reduce lifecycle emissions, the design of the blocks was adapted to integrate locally sourced prefabricated CLT designs and passive envelope features [26]. As shown in Figure 1, to simplify the building modeling, material quantifications were performed on a base module of 10 flats separated from the rest of the block by a structural expansion joint.…”

“…As highlighted in Figure 2, based on passive design guidelines given for the climate of Santiago [26], the MT building has integrated design features that reduce demands for auxiliary space-conditioning energy. These are minor measures that have little impact on the overall resources involved in manufacturing and construction but may considerably reduce emissions throughout their useful life [26].…”

“…As highlighted in Figure 2, based on passive design guidelines given for the climate of Santiago [26], the MT building has integrated design features that reduce demands for auxiliary space-conditioning energy. These are minor measures that have little impact on the overall resources involved in manufacturing and construction but may considerably reduce emissions throughout their useful life [26]. Compared to the RC building, as summarized in Table 1, these design features comprise higher envelope thermal resistances for less additional insulation (Appendix A); higher airtightness by adding a polypropylene membrane; larger room glazing-to-floor ratios for the same net glazing area (all windows being single glazing); a closer heat-storage capacity than mainstream timber frame given by the CLT structure, a 50-mm cement mortar flooring, and plaster finishes; and improved solar control through provision of operable shading blinds (Figure 2).…”

“…The results of simulations, given in kWh per square meter of floor area, were converted into GHG emissions using national emission factors [41]. Based on previous fieldwork performed for households in Santiago [26], daily and seasonal space-heating and cooling schedules were assumed for a 16-h day (7 a.m.-11 p.m.), with thermostats on the living area and bedrooms set at 17 • C from May to September (heating season) and 27 • C from December to February (cooling season). The major energy sources for space-conditioning in the MRS are liquified petroleum gas (54%), paraffin (32%), and electricity (12%) from coal, natural gas, or hydroelectricity [17].…”