Social housing retrofit: Improving energy efficiency and thermal comfort for the housing stock recovery in Mexico.

Luis Eduardo Medrano-Gómez, Azucena Escobedo Izquierdo

OVERVIEW

• Housing is one of the biggest and most complex issues in Mexico.

• There are almost 5 million abandoned.

• Causes: location, insecurity, lack of public services and poor quality of spaces and construction materials.

• Social Housing prototypes = high indoor temperatures

CURRENT PANORAMA• Residential sector occupies the

third place of total energy consumption.

• Government programs for energy efficiency with savings estimated at 3,410.72 GWh: FIPATERM – ASI

• Standards for residential energy efficiency: NOM-020-ENER-2011 and NMX-C-460-ONNCCE-2009

Step 5. Economic analysis

1

2

3

4

5

Step 3. Retrofit scenarios

Step 2. Baseline

Step 4. Simulation

Step 1. EmplacementMETHODOLOGY

H1 H2

• Jojutla – Central region of Mexico

• Semi humid warm climate

• High outdoor temperatures

Table 1. Optimum U value

Envelope component

Efficient U value

Parameterization [1] (W/m2K)

Energy saving U value

NMX-C-460-ONNCCE-2009 (W/m2K)

Roof 0.556 0.3773Walls 0.556 0.7142

Glazing 1.800 -

EMPLACEMENT

[1] Deiscy Elizabeth Sánchez Pérez. Parametrización del comportamiento térmico de la envolvente de la vivienda para la certificación de edificios sustentables. México: Programa de

Maestría y Doctorado en Arquitectura, UNAM; 2014.

Month Mean max.

temperature

(°C)

Mean min.

temperature

(°C)

Mean

temperature

(°C)

Mean temperature

oscillation

(°C)

Neutral

temperature

(°C)

Comfort Zone

(°C)

January 32.3 9.7 21.0 22.6 24.11 22.11-26.11

February 33.9 11.4 22.6 22.5 24.61 22.61-26.61

March 35.6 13.1 24.3 22.5 25.13 23.13-27.13

April 37.0 15.7 26.3 21.3 25.75 23.75-27.75

May 36.2 18.0 27.1 18.2 26.00 24.25-27.75

June 33.0 19.1 26.1 13.9 25.69 24.19-27.19

July 31.7 18.3 25.0 13.4 25.35 23.85-26.85

August 32.0 18.1 25.0 13.9 25.35 23.85-26.85

September 31.7 18.2 25.0 13.5 25.35 23.85-26.85

October 32.1 16.3 24.2 15.8 25.10 23.60-26.60

November 32.6 12.5 22.5 20.1 24.58 22.58-26.58

December 32.1 10.3 21.2 21.8 24.17 22.17-26.17

EMPLACEMENTTable 2. Thermal comfort zone

BASELINE

Construction materials:

• Multi perforated extruded block

6x12x24 cm

• Concrete beam and block system

• 3 mm/6 mm clear glass with metal

frames windows.

15.00

BEAM AND BLOCK SYSTEMU value = 3.056 W/m²K

OUTDOOR

INDOOR

OUTDOOR

U value (6 mm)= 6.998 W/m²K

INDOOR

WINDOWSU value (3 mm)= 7.082 W/m²K

INDOOR

OUTDOOR

WALLS

U value = 1.025 W/m²K

U value = 1.062 W/m²K

THERMAL AUDIT

Variable Max. Floor Min. Floor

Indoor temperature (°C) 40.41 2 22.23 1

Indoor RH (%) 78.11 1 15 2

Outdoor temperature (°C) 40.77 - 20.48 -

Outdoor RH (%) 85.27 - 9.77 -

Global solar radiation

(W/m²)

1,276.9 - 0.6 -

Table 3. Thermal audit data acquisition summary

ENERGY AUDIT

28%

50%

4%

18%

Energy balance

Ventilation

Miscellaneous

Computer

Lighting

RETROFIT SCENARIOS• Roof – Polyurethane insulation 5.08 cm

• Walls – Polyurethane insulation 2.54 cm

• Windows – Solar control film R20 Silver

and aluminum frames

• A/C System – 1TR/110V with EER 9.70

INDOOR

U value = 0.414 W/m²K

OUTDOOR

WALLSU value = 0.4512 W/m²K

BEAM AND BLOCK SYSTEMU value = 0.3487 W/m²K

15.00

OUTDOOR

INDOOR

OUTDOOR

INDOOR

WINDOWSU value = 0.94 W/m²K

SIMULATION

SIMULATION

SIMULATION

House

Base Case

Annual

consumption

(kWh/year)

Base Case

Monthly

consumption

(kWh/month)

Retrofit Case

Annual

consumption

(kWh/year)

Retrofit Case

Monthly

consumption

(kWh/month)

Reduction

after retrofit

(%)

H2 4,806.76 400.56 2,525.93 210.49 53

H1 6,999.89 583.32 4,397.67 366.47 63

Table 4. Air conditioning electric consumption

ECONOMIC ANALYSIS

H1 H2

Retrofit cost (MXN) $23,444.10 $28,398.05

Max. Financing (MXN) $49,737.32 $49,737.32

18-month payment (MXN) $1,472.58 $1,783.75

30-month payment (MXN) $948.02 $1,148.35

Cost per square meter (MXN) $2,175.32 $2,175.32

Incremental per square meter (MXN) $266.17 $328.07

Incremental (%) 12.24 15.08

Table 5. Retrofit costs and financing

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