Table 1
Design and operational parameters of the office building archetypes.
| ARCHETYPE I | ARCHETYPE II | ARCHETYPE III | |
|---|---|---|---|
| Number of floors | 8 | 16 | 8 |
| Floor layout | Cellular | Cellular | Open |
| Building footprint (m) | 20 × 30 | 20 × 30 | 20 × 30 |
| Gross floor area (m2) | 4,800 | 9,600 | 4,800 |
| Floor height (m) | 2.8 | 2.8 | 2.8 |
| Number of elevators | 2 | 3 | 2 |
| External wall structure | 2.5 cm plaster + 9 cm brick + 2.5 cm plaster | 2.5 cm plaster + 13.5 cm brick + 2.5 cm plaster | 2.5 cm plaster + 9 cm brick + 2.5 cm plaster |
| Internal wall structure | 2.5 cm plaster + 9 cm brick + 2.5 cm plaster | ||
| Roof structure | 10 cm concrete + 6 cm air + 0.6 cm fibre cement roof tile | ||
| Floor structure | Internal: 1.25 cm acoustic ceiling + 10 cm concrete + 0.5 cm carpet External: 20 cm concrete + 0.5 cm carpet | ||
| Internal wall area per floor (m2) | 179.9 | 144.6 | 40.2 |
| Glazing thickness (mm) | 6 | 6 | 6 |
| Glazing thermal transmittance (W/(m2.K)) | 5.782 | 5.782 | 5.782 |
| Internal loads schedule | 0600–1800 hours on weekdays | 0600–1800 hours on weekdays | 0600–1800 hours on weekdays |
| Occupant density (people/100 m2) | 11 | 11 | 11 |
| Lighting use intensity (W/m2) | 10.5 | 10.5 | 10.5 |
| Equipment use density (W/m2) | 14 | 14 | 14 |
| Mechanical ventilation: fresh air intake (L/s/person) | 7.5 | 7.5 | 7.5 |
Table 2
Parameters and their possible input values.
| PARAMETER | POSSIBLE INPUT VALUES | EXPLANATION OF THE CHOSEN VALUES | ||
|---|---|---|---|---|
| CITY | CDH | ELECTRICITY MIX (kg CO-eq/kWh) | ||
| Citya | São Paulo | 14,172 | 0.233 | The 12 largest cities with at least two in each region of Brazil (for a map with the selected cities, see Section 2 in the supplemental data online) |
| Rio de Janeiro | 45,016 | 0.233 | ||
| Brasília | 16,624 | 0.154 | ||
| Salvador | 67,930 | 0.402 | ||
| Fortaleza | 71,394 | 0.402 | ||
| Belo Horizonte | 23,883 | 0.233 | ||
| Manaus | 82,005 | 0.206 | ||
| Curitiba | 9,397 | 0.143 | ||
| Recife | 63,550 | 0.402 | ||
| Goiânia | 31,081 | 0.154 | ||
| Belém | 81,393 | 0.206 | ||
| Porto Alegre | 23,954 | 0.143 | ||
| Building archetype | I, II, III | Archetypes defined in NBR 12721 (ABNT 2006) | ||
| Window-to-wall ratio (WWR) | 30%, 50%, 70%, 90% | Full range of possible values | ||
| Solar heat gain coefficient (SHGC) | 0.2, 0.4, 0.6, 0.8 | Full range of possible values | ||
| Window opening effective area | 0.0b, 0.1, 0.3, 0.5, 0.7, 0.9 | Full range of possible values | ||
| Shading | 0.0, 0.2, 0.4, 0.6, 0.8, 1.0 | Full range of possible values | ||
| Cooling set point (°C) | 22, 23, 24, 25 | Based on Lamberts et al. (2015) | ||
| Coefficient of performance (COP)c | 2.0, 2.5, 3.0, 3.5, 4.0 | Based on Inmetro (2017) and Lamberts et al. (2015) | ||
| Building lifetime (years) | 50, 75, 100 | Recommended minimum of 50 years (ABNT 2013), but 100 years is assumed as a maximum for a concrete structure | ||
| Component service time multiplier | 75%, 100%, 125% | Assumed based on the literature (see Section 3.2 in the supplemental data online) | ||
[i] Note: a City determines the climate and electricity mix. Climate is represented by cooling degree-hours (CDH), measured using a wet-bulb temperature of 15°C (Versage et al. n.d.). Electricity mix scores were sourced from the ecoinvent v3.7.1 database (allocation cut-off), measured using GWP100 metrics, Intergovernmental Panel on Climate Change (IPCC) (2013) method.
b A window opening effective area of 0.0 represents a building with no natural ventilation (fully air-conditioned—AC).
c COP was decreased by 0.5 to account for distribution losses.
Table 3
Median with quartiles, minimum and maximum greenhouse gas (GHG) emissions by life-cycle module. Some modules were grouped for convenience.
| GHG EMISSIONS (kg CO2-eq/m2 GFA/year) | |||||||
|---|---|---|---|---|---|---|---|
| A1–A4 | A5 | B4 | B6 | C1 | C2–C4 | TOTAL | |
| Minimum | 3.63 | 0.02 | 2.79 | 11.87 | 0.29 | 0.16 | 20.22 |
| 25th percentile | 4.86 | 0.04 | 3.95 | 17.73 | 0.39 | 0.21 | 30.74 |
| Median | 5.96 | 0.05 | 5.18 | 26.04 | 0.41 | 0.25 | 38.61 |
| 75th percentile | 7.36 | 0.08 | 6.92 | 43.79 | 0.58 | 0.33 | 57.00 |
| Maximum | 10.01 | 0.19 | 9.45 | 95.77 | 0.81 | 0.43 | 106.39 |
[i] Note: A1 = raw material extraction and processing; A2 = transport to the manufacturer; A3 = manufacturing; A4 = transport to the building site; A5 = installation in the building; B4 = replacement; B6 = operational energy use; C1 = deconstruction, demolition; C2 = transport to waste processing; C3 = waste processing for reuse, recovery and/or recycling; and C4 = disposal.
Figure 1
Greenhouse gas (GHG) emissions by life-cycle modules: (a) material production and transport; (b) material replacement; and (c) operational energy use. Only materials of at least 5% contribution to impacts are included.
Figure 2
Greenhouse gas (GHG) emissions as a function of the city. The buildings are divided into fully air-conditioned (AC) and mixed mode (MM). The cities are ordered according to their cooling degree-hours (CDH).
Table 4
Results of the multivariate regression analysis of GHG emissions by cooling strategy.
| INDEPENDENT VARIABLE | MIXED-MODE BUILDINGS | FULLY AIR-CONDITIONED BUILDINGS | ||
|---|---|---|---|---|
| ADJUSTED R2 = 0.966 | ADJUSTED R2 = 0.963 | |||
| STANDARDISED COEFFICIENTS | 95% CI | STANDARDISED COEFFICIENTS | 95% CI | |
| Electricity mix | 0.79 | (0.77, 0.80) | 0.79 | (0.75, 0.82) |
| Climate (CDH) | 0.23 | (0.21, 0.25) | 0.22 | (0.19, 0.26) |
| Archetype II (versus Archetype I) | 0.09 | (0.08, 0.11) | 0.06 | (0.02, 0.10) |
| Archetype III (versus Archetype I) | 0.07 | (0.06, 0.08) | 0.02 | (–0.02, 0.05) |
| Window-to-wall ratio (WWR) | 0.02 | (0.00, 0.03) | 0.03 | (0.00, 0.06) |
| Solar heat gain coefficient (SHGC) | 0.06 | (0.05, 0.07) | 0.07 | (0.04, 0.10) |
| Window opening effective area | –0.09 | (–0.11, –0.08) | – | – |
| Shading | –0.04 | (–0.05, –0.02) | –0.05 | (–0.08, –0.02) |
| Cooling set point | –0.07 | (–0.08, –0.05) | –0.07 | (–0.10, –0.04) |
| Cooling efficiency | –0.17 | (–0.19, –0.16) | –0.23 | (–0.26, –0.20) |
| Building lifetime | –0.08 | (–0.09, –0.07) | –0.06 | (–0.10, –0.03) |
| Component service life multiplier | –0.10 | (–0.11, –0.08) | –0.08 | (–0.11, –0.05) |
[i] Note: CDH = cooling degree-hours; and CI = confidence interval.
Figure 3
Standardised regression coefficients (SRCs) resulting from a multivariate regression analysis of greenhouse gas (GHG) emissions of mixed-mode (MM) buildings, plotted as a function of cooling degree-hours (CDH). Only parameters with are shown. Negative values are shown on the y-axis.