Self-build amid rising temperatures: the case of Cantinho do Céu, São Paulo

Cavalcanti, Cristina Kanya Caselli; Alvim, Angélica Aparecida Tanus Benatti

doi:10.1590/2236-9996.2020-4905

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dossiê: macroeconomia e desenvolvimento metropolitano, regional e local • Cad. Metropole 22 (49) • Sep-Dec 2020 • https://doi.org/10.1590/2236-9996.2020-4905 copy

Self-build amid rising temperatures: the case of Cantinho do Céu, São Paulo

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

This article seeks to identify the main envelope elements that hinder the thermal performance of self-construction in a context of rising temperatures, an important effect of climate change. Based on a set of self-built houses located in Cantinho do Céu, an irregular settlement in the southern region of São Paulo, we used an evaluation method that combines the analysis of the building envelopes with field research, interviews, and thermographic photographs. The results indicate that the heating of the dwellings is predominantly related to the inappropriate use of materials and to the wrong disposition of construction elements. Technical advice is recommended as a tool that acts on the construction defects of precarious housing, contributing to a better adaptation of the most vulnerable population to climate effects.

climate change; heating; self-construction; technical advice; Cantinho do Céu - São Paulo

Climate change	Consequences for population	Effects on housing
Intense heat	Increased need for cooling Reduction in quality of life of population due to ill-adapted housing Greater impact on high-risk populations (elderly, infants and poor) Deterioration in air quality	Thermal characteristics of masonry Windows (placement, sealing and sizing) Thermal characteristics of roofing
Drought	Water shortages affecting population and commercial activities Reduced potential for electricity generation Increased migratory flow	Water-saving devices Rainfall collection Reuse of graywater Use of biodigestor septic tank Impermeable areas negatively impact water cycle, hampering maintenance of levels of water bodies Rational water use in the home can help maintain reservoir levels Not directly linked to construction, but vulnerabilities exacerbated by it can be a factor determining migrations
Intense precipitation	Increase in frequency and intensity of precipitation, flood and inundations	Watertightness of roofing Sturdiness of roofing Resistance of roofing materials against rain and wind

Bioclimatic Zone	Component	Solar absorptance (dimensionless)	Thermal transmittance W/(m²K)	Thermal capacity KJ(m²K)
ZB 3	Masonry	a ≤ 0,6 a > 0,6	U ≤ 3,70 U ≤ 2,50	≥ 130 ≥ 130
	Roof	a ≤ 0,6 a > 0,6	U ≤ 2,30 U ≤ 1,50	no requirement no requirement
	Openings			usable area (A)
		medium ventilation openings		A ≥ 8%
		allow the sun in winter		A ≥ 12%

Sector	Monthly income (R$)	Population	Vulnerability	House number
Sector	Per capita (2010)	Inhabitants (2010)	IPVS (2010)	House number
355030830000132 355030830000200 355030830000203 355030830000243 355030830000273 355030830000274 355030830000294 355030830000385 355030830000386 355030830000420	444,84 493,99 490,84 564,30 488,97 567,96 371,79 461,17 466,47 583,50	1.079 1.033 858 1.210 380 1.080 564 622 1.115 768	4 6 6 5 4 5 6 4 6 3	6 5,7,8,9,10 1 2,11,15 31 3 ,4,13,14,27,28,29,30,31,32 25, 26 16,17,18, 19,21, 22, 23, 24 20 12

Roof type	Frequency	%
Slab Slab + shingles Slab + solid floor Shingles Shingles + ceiling liner	12 11 1 5 3	37.5 34.38 3.13 15.63 9.38
Total	32	100.00

House	H E A T W A V E S
House	Slab without roofing shingles	Fiber-cement roofing shingles	Windows opening onto narrow corridors	Spaces without opening to the outside	Rooms without openings	Openings on same wall
1	1
2				1
3			1	1
4		1	1	1
5			1	1
6	1			1
7			1	1
8		1	1			1
9			1
10					1
11				1	1
12
13			1
14			1	1	1
15
16			1	1		1
17
18		1	1
19			1	1
20		1	1
21
22	1			1	1
23			1	1
24			1			1
25			1	1	1
26					1
27			1
28			1	1
29			1	1	1
30			1	1	1
31	1		1
32			1
Total	4	4	21	16	8	3

N A T U R A L V E N T I L A T I O N
Houses	Kitchen					Living room					Bedroom
Houses	Floor area	Ventilation area	8%	Compliant?	Outer	Floor area	Ventilation area	8%	Compliant?	Outer	Floor area	Ventilation area	8%	Compliant?	Outer
house 2	17,30	0,84	1,38	no	yes	17,97	0,60	1,20	no	no	17,30	0,60	1,38	no	yes
house 3	10,05	0,76	0,80	no	yes	13,80	0,64	1,10	no	yes	13,75	0,93	1,10	no	no
house 4	18,41	0,46	1,47	no	yes	integrated kitchen and living room					14,26	0,48	1,14	no	yes
house 5	12,45	1,36	1,00	yes	no	12,59	0,71	1,01	no	no	11,56	0,39	0,92	no	yes
house 7	7,76	0,45	0,62	no	yes	12,32	0,71	0,99	no	yes	8,57	0,59	0,69	no	yes
house 8	13,38	0,81	1,07	no	yes	integrated kitchen and living room					13,48	0,46	1,08	no	yes
house 9	11,08	0,76	0,89	no	no	10,57	1,10	0,85	yes	yes	7,88	0,73	0,63	yes	no
house 11	9,99	0,61	0,80	no	no	12,22	1,11	0,98	yes	yes	12,15	0,51	0,97	no	no
house 13	15,49	0,50	1,20	no	yes	18,52	0,00	1,20	no	no	10,12	0,46	0,81	no	yes
house 14	12,13	0,95	1,20	no	yes	9,49	1,13	0,76	yes	no	14,53	1,11	1,16	no	no
house 17	11,87	0,48	0,95	no	yes	16,77	0,60	1,34	no	yes	6,41	0,48	0,51	no	yes
house 18	11,21	0,70	0,90	no	yes	10,66	0,49	0,85	no	yes	11,21	0,46	0,90	no	yes
house 22	10,27	0,00	0,82	no	yes	8,31	0,48	0,66	no	yes	14,20	0,42	1,14	no	yes
house 28	7,97	0,80	0,64	yes	no	absent					8,44	0,60	0,68	no	yes

N A T U R A L L I G H T I N G
Houses	Kitchen					Living room					Bedroom
Houses	Floor area	Light area	12,5%	Compliant?	Outer	Floor area	Light area	12,5%	Compliant?	Outer	Floor area	Light area	12,5%	Compliant?	Outer
house 2	17,30	0,78	1,88	no	yes	17,97	1,05	1,88	no	no	17,30	0,68	1,88	no	yes
house 3	10,05	0,73	1,26	no	yes	13,80	1,13	1,73	no	yes	13,75	1,64	1,72	no	no
house 4	18,41	0,81	2,30	no	yes	integrated kitchen and living room					14,26	0,54	1,78	no	yes
house 5	12,45	1,26	1,56	no	no	12,59	1,22	1,57	no	no	11,56	0,36	1,44	no	yes
house 7	7,76	0,42	0,97	no	yes	12,32	1,03	1,54	no	yes	8,57	0,66	1,07	no	yes
house 8	13,38	0,76	1,67	no	yes	integrated kitchen and living room					13,48	0,52	1,69	no	yes
house 9	11,08	0,71	1,39	no	no	10,57	1,79	1,32	yes	yes	7,88	0,82	0,98	no	no
house 11	9,99	0,57	1,25	no	no	12,22	1,11	1,53	no	yes	12,15	1,06	1,52	no	no
house 13	15,49	0,88	1,94	no	yes	18,52	2,17	2,32	yes	no	10,12	0,52	1,26	no	yes
house 14	12,13	0,95	1,52	no	yes	9,49	1,13	1,19	no	no	14,53	1,25	1,82	no	no
house 17	11,87	0,84	1,48	no	yes	16,77	1,05	2,10	no	yes	6,41	0,54	0,80	no	yes
house 18	11,21	0,65	1,40	no	yes	10,66	0,56	1,33	no	yes	11,21	0,51	1,40	no	yes
house 22	10,27	0,00	1,28	no	yes	8,31	0,54	1,04	no	yes	14,20	0,39	1,78	no	yes
house 28	7,97	0,75	1,00	no	no	absent					8,44	0,68	1,06	no	yes

Roofing materials	a	R (m²K/W)	U (W/m²k)	U NBR	ϕ (hours)	ϕ NBR	Ct	Ct NBR
Fiber-cement shingles	0,50*	0,22	4,6	U≤ 2,30	0,1	≤ 3,3	12,8	I
Pre-cast slab with hollow ceramic tiles + premix mortar underside	0,65**	0,35	2,8	U≤ 1,5	5,4	≤ 3,3	204,8	I
Fiber-cement shingles + slab + premix mortar underside	0,50*	0,38	2,6	U≤ 2,30	4,1	≤ 3,3	247,5	I
Fiber-cement shingles + ceiling lining	0,50*	0,36	2,8	U≤ 2,30	0,4	≤ 3,3	15,4	I

Walling materials	a	U (W/m²k)	U NBR	R (m²K/W)	ϕ (hours)	ϕ NBR	Ct	Ct NBR
Finished masonry, blocks and gray premix mortar finish	0.30**	2.4	U≤ 3.7	0.41	3.5	≤ 4.3	140.3	≥ 130
Finished masonry, blocks and white premix mortar finish	0.158**	2.4	U≤ 3.7	0.41	3.5	≤ 4.3	140.3	≥ 130
Masonry with internal but no external finish (on blocks)	0.65**	2.6	U≤ 2.5	0.36	4.2	≤ 4.3	90.3	≥ 130

Climate	Construction	Description
Extreme temperatures	Slab without roofing shingles	As seen in the review of the materials and their thermal characteristics, concrete slabs without roofing shingles fail to meet performance specifications in standard (NBR no. 15.220), and may result in overheating of the interior and greater use of electricity (air-conditioning).
	Fiber-cement roofing shingles	Fiber-cement roofing shingles fail to meet performance specifications in standard (NBR no. 15.220), and may result in overheating and greater use of electricity (air-conditioning).
	Windows opening onto narrow corridors	The close proximity of the houses and perimeter walls hamper air flow, restricting refreshing of internal air . This proximity also limits natural lighting , remedied by use of electric lighting.
	Space without opening to the outside	Space with opening to other internal spaces was common, such as bedroom with window opening onto living room. This type of strategy restricts refreshing of air and exploitation of natural ventilation and natural lighting.
	Rooms without openings	The absence of openings in a space prevents natural ventilation and lighting , leading to higher electricity costs for artificial lighting and conditioning of the space.
	Openings on same wall	Natural ventilation is facilitated by the positioning of openings in facing or adjacent walls. When a residence has windows all set in the same wall there is no cross ventilation .

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