CAPÍTULO II: El Problema, Objetivos, Hipótesis, y Variables
2.1 PLANTEAMIENTO DEL PROBLEMA
2.1.1 Descripción de la Realidad Problemática
165
Figure 53 Prevalence of main participants’ health status in relation to study group.
9.3 Nature and extent of the intervention
The retrofit intervention implemented by SECCCA was a purposive measure that consisted of a retrofit or refurbishment (Sustainability Victoria 2012) based on the recommendations of an external energy consultant and approved by the householders. The retrofits consisted mainly of draught proofing and roof insulation top‐up in the sixteen intervention homes with one home receiving an additional reverse cycle air conditioner, one home receiving a gas fuelled water heater, and one home choosing the installation of Renshade (that is, an internally applied solar screen that blocks an estimated 85 per cent of inward radiant heat flow) (Wren Industries 2015). Sealing measures included the sealing of external doors, the sealing of internal doors of rooms that had permanently vented windows, such as some bathrooms, toilets and laundries, of ceiling vents and, in two cases, gaps where windows joined the wall.
In addition, householders performed independent actions during the study period to improve their homes. In the intervention group, two householders funded new reverse cycle air conditioners (RC ACs) for heating and cooling and one household invested in a new ducted evaporative cooling system. With regard to room conditioning, in the control group, two household installed new RC ACs and one household an electric heater for the bedroom. A gas wall heater was replaced in one home and ceiling fans installed in another. Table 29 lists the energy modifications through the ESS and through self‐funded activities in the control and intervention groups. Table 64 to Table 66 in the appendix list the gross floor areas, FirstRate star ratings, air tightness levels, heating system
characteristics, the retrofit details for the intervention homes and the independent actions for each homes in the two groups.
Do you or anyone else smoke in this home? ‐ Yes Do you have any long‐standing illness, disability or
infirmity? ‐ Yes
Do you have an impairment that prevents you from getting around or taking care of yourself? ‐ Yes Have you experienced any wheezing or whistling in
the chest in the last 12 months? ‐ Yes Have you experienced any asthma or chronic obstructive pulmonary disorder (COPD) during the
last 12 months? ‐ Yes
Main participants' health status (Baseline, winter 2014)
Control group (N=13) Intervention group (N=16)
166 Type of energy modification activities in homes by the end of the study (N=29) and prevalence by study groups
Control group
(N=13; 45% of homes)
Intervention group (N=16; 55% of homes)
Intervention n %ᵃ n %ᵃ
Retrofit of thermal envelope
Insulation
Ceiling/ roof insulation top‐up with R4.0 material
0 0% 16 100%
Draught proofing
Draught roofing of external doors 0 0% 15 94%
Draught sealing of internal doors to permanently vented rooms
0 0% 9 56%
Sealing of exhaust fans 0 0% 3 19%
Covering of down lights 0 0% 3 19%
Sealing of duct outlets/ wall gaps 0 0% 2 13%
Solar protection
Ren shade 0 0% 1 6%
New internal blinds 0 0% 1* 6%
Upgrade of space heating/ cooling systems
Heating/ cooling appliance upgrade/ modification 0%
New reverse cycle air conditioner 3.5kW for heating and cooling
3* 23% 1 + 2* 19%
New evaporative cooling 0 0% 1* 6%
New portable cooler (addition) 0 0% 1* 6%
Use of electric portable heater (addition) 1* 8% 1* 6%
Use of electric portable heater (replacement of unflued gas heater)
0 0% 1* 6%
New ceiling fans 2* 15% 1* 6%
Upgrade/ changes to HWS, lighting and electrical appliances
0%
Hot water system (HWS) upgrade
New hot water system (replacement) 2* 15% 1 + 1* 13%
Insulation of HWS pipes 0 0% 7 44%
Lighting upgrade/ modification LED globes and/ or LED down lights (replacements)
0 0% 8 50%
Appliance upgrades
New LED TV (replacement) 0 0% 1 6%
New TV (technology unknown) (replacement)
1* 8% 0 0%
New LED smart TV (addition) 0 0% 1* 6%
ᵃ Valid per cents within study group
* Independent action
Table 29 Type of energy modification activities in homes by the end of the study (N=29) and prevalence by study groups
167 9.3.1 Changes in home energy efficiency star ratings
The star ratings of the homes were derived from a combination of FirstRate5 assessments and estimations using a standard house in the AccuRate software package as explained in Section 8.3.10.1.5.1. The average star ratings of the control and the intervention groups were comparable with 2.9 stars and 2.7 stars respectively, when assessed by FirstRate. The retrofits consisted primarily of draught proofing and top‐up insulation. The retrofits lifted the mean star rating of the intervention group homes by 0.8 stars to 3.5 stars, a rating that was still below the mandatory 5 star rating introduced in Victoria in 2006. Only one home, achieved a 6 ‐Star rating (rounded from 5.6 stars) that is currently the mandatory minimum standard for new homes. This home already had a comparatively high star rating of 5.1 stars at the baseline. Independent action by householders did not influence the star ratings as these home improvements to the space conditioning systems did not alter insulation levels, shading or thermal mass of the homes. Table 30 and Table 31 present the changes in star ratings due to the retrofit intervention.
Descriptive statistics of FirstRate assessed star ratings in relation to study groups, before and after the retrofit intervention
Control group (N=9) Intervention group (N=10)
Stars Pre‐retrofit (Stars) Post‐retrofit (Stars) Improvement (Stars)
Minimum 1.5 0.6 2
Average 2.9 2.7 3.5 0.8
Maximum 4.4 5.1 5.6
Table 30 Descriptive statistics of FirstRate assessed star ratings in relation to study groups, before and after the retrofit intervention
Descriptive statistics of combined (FirstRate assessed and estimated) star ratings in relation to study groups, before and after the retrofit intervention
Control group (N=13)
Intervention group (N=15)
Stars Pre‐retrofit (Stars) Post‐retrofit (Stars) Improvement (Stars)
Minimum 1 0.6 2
Average 2.8 2.8 3.6 0.8
Maximum 4.4 5.1 5.6
Table 31 Descriptive statistics of combined (FirstRate assessed and estimated) star ratings in relation to study groups, before and after the retrofit intervention
168
Figure 54 FirstRate assessed star ratings in relation to study groups and study periods
Figure 55 Combined (FirstRate assessed and estimated) star ratings in relation to study groups and study periods
9.3.2 Changes in air tightness
The air tightness of homes was derived from combining actual measurement by a Blower Door Test and estimations using a practice based estimation tool (cf. Section 8.3.10.1.5.2). The air tightness of all homes at the baseline was considered poor (Energy Leaks Pty. Ltd. as cited in Reardon 2013) with air change rates at 50 Pascal (ACH50) values around 20 per hour. Leaks in the building envelope were apparent around windows and doors (Figure 56), as wall vents and vented bathrooms.
After the draught proofing, the air change rate at 50 Pascal of the intervention group improved to a fair ranking (Energy Leaks Pty. Ltd. as cited in Reardon 2013), that is, measured ACH50 14.37 1/h or combined (measured and estimated) ACH50 15.85 1/h. Table 32 and Table 33 present the changes in air change rates at 50 Pascal (ACH50) due to the retrofit intervention.
Control group (n=9) Intervention group pre‐intervention
(n=10)
Intervention group post‐intervention
(n=10)
Star rating
Groups and study periods
FirstRate assessed star ratings in relation to study groups and study periods
0
Control group (n=13) Intervention group pre‐intervention
(n=15)
Intervention group post‐intervention
(n=15)
Star rating
Groups and study periods
Combined (FirstRate assessed and estimated) star ratings in relation to study groups and study periods
169
Figure 56 Example of air leaks in building envelope due to wear and tear (House 2)
Descriptive statistics of measured air change rates in relation to study groups, before and after draught proofing
Control group (N=7)
Intervention group (N=7)
Pre‐DP* Post‐DP*
ACH50 (1/h) ACH50 (1/h) ACH50 (1/h) % improvement
Minimum 14.36 12.99 10.1
Average 19.59 20.47 14.37 30%
Maximum 25.1 31.9 21.77
*DP — Draught proofing
Table 32 Descriptive statistics of measured air change rates in relation to study groups, before and after draught proofing
Descriptive statistics of combined (measured and estimated) air change rates in relation to study groups, and before and after draught proofing
Control group
(n=13)
Intervention group (n=16)
Pre‐DP* Post‐DP*
ACH50 (1/h) ACH50 (1/h) ACH50 (1/h) % improvement
Minimum 14.05 12.98 10.1
Average 20.36 21.08 15.85 25%
Maximum 29.20 33.98 23.29
*DP — Draught proofing
Table 33 Descriptive statistics of combined (measured and estimated) air change rates in relation to study groups, before and after draught proofing
170 Figure 57 Measured air change rates in relation to study groups and study periods
Figure 58 Combined (measured and estimated) air change rates in relation to study groups and study periods
0 5 10 15 20 25 30 35
Control group (n=7) Intervention group pre‐
intervention (n=7)
Intervention group post‐
intervention (n=7)
Air changes per hour at 50 Pascals (1/h)