Evaluating Thermal Insulation Strategies for High-Rise Residential Buildings in Sarajevo

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

General Comments

This paper explores the effectiveness of improved insulation on resident satisfaction in three residential buildings in Bosnia and Herzegovina. There are some interesting observations in this paper, but the key research questions and contributions to the literature are not very clear. From reading the abstract, I was expecting some comparison of the relative costs and health and environmental impacts of alternative insulation materials in the paper, but there is no such quantitative comparison (only a table listing their relative thermal conductivity, but nothing on the relative costs or impacts). There are a few places where different insulation materials are discussed, but none of that discussion seems relevant to the main focus of the paper. There are no assessments of the relative benefits of different insulating materials or survey questions asking residents about different types of insulation, etc. I can understand a little discussion on alternative materials but there seems to be a disproportionate amount of text spent on discussing alternative materials when there’s no new analysis of alternative insulation materials provided in this study. In addition, there are findings from a survey with a low response rate presented without descriptive data to indicate how representative of a sample was achieved. There seem to be contradictory findings that energy consumption fell substantially after renovation (e.g., Table 7) and that residents noticed improvements in temperature consistency and a very high share of respondents indicated they were satisfied with the renovation work, but that people weren’t really saving any money (why are they paying the same amount if building energy consumption fell?) and text indicating that it was hard to get residents to be willing to accept paying for renovations, even with cost-share from the public sector, because they didn’t anticipate any savings. What are the primary takeaways that readers should have from reading this paper? Overall, it seems like the main message is that increasing insulation in residential building in BiH may not be very beneficial. It would be helpful if the authors could provide a clearer picture of what alternative strategies could potentially make increased thermal insulation beneficial to the residents of BiH as well as some assessment of what those benefits would be.

Specific Comments

1. The abstract is well-written but would benefit from a clearer indication of the primary contributions of this research as well as key findings.
2. Line 36. I think “… escalating urban climate change…” is unclear and the text should instead refer to escalating urban contributions to climate change through rising GHG emissions from cities.
3. Lines 42-43. Primary factor influencing energy expenditure holding everything else constant? Seems like building design, fuel type, building size, number and type of appliances, lighting characteristics, efficiency of heating and cooling system, and other factors could be at least as important as thermal insulation in influencing energy expenditures.
4. Line 46. What is EPS market share in BiH?
5. Lines 47-53. What are the boundaries of your analysis? Are you planning to do a more complete life cycle analysis, including emissions associated with the production of EPS?
6. Lines 288-289. How did the authors evaluate how representative their sample is of the relevant population, especially given a response rate of only 19%?
7. Lines 362-364. Why do the utility bills remain almost the same with improved energy efficiency? Sounds like the main benefit is improved comfort overnight when the heat is turned off and the temperature now remains more constant rather than dropping so much, but shouldn’t energy requirements fall if the building temperature remains higher in the morning than without the energy efficiency improvements (i.e., less heating required to reach the desired temperature)? Or maybe that relates to the authors’ point about some tenants opening some of their windows because the building is now getting too hot because the heat is being used during certain hours regardless of the actual temperature inside the building. I suggest the authors add some policy implications of their work, for instance that changing the way in which utilities are operated may incentivize investments in greater energy efficiency.
8. Table 7. If energy consumption is falling substantially after renovation, why are energy costs not falling (as mentioned in line 406)?

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors study thermal insulation for enhancing energy efficiency and improving indoor living conditions. Emphasis is in dense urban environments with aging buildings, where inferior construction practices has deteriorate building quality, augment energy consumption and diminish quality of life. Expanded polystyrene is the dominant insulation material in BiH, due to its cost-effectiveness. Recent advances in sustainable insulation materials, such as cellulose, wool, hemp fibers, and aerogel offer environmentally friendly and sustainable alternatives. The authors evaluate the effectiveness of thermal refurbishments in high-rise residential buildings in Sarajevo, focusing on energy efficiency and resident satisfaction. To this end, they combine case studies, surveys, and expert interviews to provide insights into improving indoor conditions with sustainable construction practices.

 

The authors should address the following issues in a significantly improved version of their manuscript:

 

Please shortly describe the paper’s structure at the end of the Introduction section.

 

Page 5: more details for the questionnaire survey are needed: A Table with the number of questionnaires distributed, the number answered and the main statistics of the sample of people approached with the questionnaires.

 

Lines 168-169 please insert some citation for the company project.

Lines 289-290: is the same central heating schedule kept with the renovated building?

Figure 2a: which is the origin of these damages to the external walls’ sheathing?

 

Figure 1: Is it possible to indicate the position of the river in this map?

 

Table 8: an additional column with approximate costs would be helpful here.

 

Table 7: why the average ambient temperatures differ between the three buildings?

Would be better to add average lowest temperatures during the winter months, or degree-days if available.

 

Line 395 and Table 7: which are the units for energy consumption. Can you express in annual kWh/m2 useful area?

It is peculiar that you do not find significant reduction in consumption of the renovated building. Ths needs more discussion. Try to normalize with average temperature difference (e.g. set point room temperature minus average winter temperature). What about the boilers? Did you change them or fitted with improved burners? Do you have efficiency measured?

 

Lines 402-410: What is the heating control system for the buildings? Do you control the boiler water supply temperature based on the outdoor temperature levels?

 

The Conclusions section could possibly include some quantitative results of this study. Do you have some heating energy consumption reduction?

 

Line 601 and beyond: An additional appendix is necessary with the main technical specifications of the heating systems of the three buildings (Nominal boiler rating, type of fuel, two-pipe hydronic (vertical?) distribution system type of room terminals etc.). 

 

English language needs minor improvements.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I felt the authors were responsive to review comments and made several revisions that I thought made the paper clearer, more focused, and more concise. I think the clarification that the central district heating company charges the same amount per square meter of heated area regardless of energy use is an important addition and helps explain the limited incentives for improved energy efficiency in high-rise residential buildings in Sarajevo. Improving the economic efficiency of the energy sector in BiH by incentivizing greater energy efficiency (e.g., charging for energy use based on the quantity used, installing individual apartment temperature regulation and meters of energy use) would certainly be expected to help make energy use more efficient and should increase the value of those apartments relative to those that are not individually metered and are less energy efficient, other things being equal. When I asked how representative the sample of respondents is of the relevant population, I meant assessing things like the demographic composition, etc. (e.g., age, gender, income, or other factors that might be expected to influence survey responses) to explore the extent to which respondents differed from the overall population of the apartment building. In that case, the survey results may be biased relative to the full population of each apartment building. However, I am not sure if such information is available for the non-respondents.

Author Response

Thank you very much for taking the time to review this manuscript.

In order to provide a more thorough presentation of the policy implications, a sentence has been added to both the introduction (lines 69-73) and the discussion section (lines 478-483).

With regard to the demographic specifics of the survey, it is regrettable to note that these data were not documented. However, observations during the survey revealed that the population of these high-rise buildings was diverse, including students, families of various sizes, singles, and retirees.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The revised manuscript is acceptable for publication.

Author Response

Thank you very much for taking the time to review this manuscript.