Behavioural Change as a Domestic Heat Pump Performance Driver: Insights on the Influence of Feedback Systems from Multiple Case Studies in the UK

Round 1

Reviewer 1 Report

This study examines the role of user behaviour and how performance could be improved from a systems perspective. A sample of 21 case studies was selected from 700 domestic HPs monitored across the UK via the government’s Renewable Heat Premium Payment Scheme for the collection of qualitative and quantitative socio-technical data. 

The paper is relevant to the theme of the journal and will contribute to academic debate. The abstract is OK and well structured. In my opinion, the subject matter of the research problem is highly appreciable. It will make contributions to the relevant field of research. The presentation of thoughts in the paper is notable. However, the author(s) did not include, strong research implications. This is important considering the fact that the readers will want to know what is new in the paper. Also, the purpose of the paper is not clear. The rationale behind conducting this research is not clear i.e. why are they pursuing this research?
5-In addition, the authors need to provide their justification with regards to their novelty in this paper/ contributions to knowledge and cite more recent (2017-2022)

Author Response

We would like to kindly thank you for your thoughtful and thorough review of the manuscript. We agree with the comments and have revised the manuscript according to the suggestions provided. Any changes/additions in the revised manuscript are highlighted using track changes. Please also see attached for our detailed responses to your comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors examine the relationship between user behaviors and the efficiency of heat pumps. The manuscript includes new
and valuable information and it fits the topic of the journal can be published with some minor changes:
 - There are some typos,
 - Reference numbering must start from 1 not with 2
 - In Figure 1, 3 font size is so small, it must be increased
 - Some names are written wrong e.g. Ref.42
 - what do the authors mean in line 435?
 - Line 54-55 rephrase: there is not a pumping process in the cooling cycle of HP, the refrigerant flows with pressure differences
 - Line 57-58 rephrase : this is true for the cooling mode of a heat pump. When the temp. in the heat sink is lower, efficiency is lower for heating mode because the heat pump cannot extract larger amounts of heat.
 - Line 301 : For the used software, is there a reference or is it developed by the authors?
 - Line 393-394 what is "the effective compared to design heat load ratio"

Author Response

We would like to kindly thank you for your thoughtful and thorough review of the manuscript. We agree with the comments and have revised the manuscript according to the suggestions provided. Any changes/additions in the revised manuscript are highlighted using track changes. Please also see attached for our detailed responses to your comments.

Author Response File: Author Response.pdf

Reviewer 3 Report

Some questions and suggestions are as follows:

1. Based on the case studies, causal loop diagrams of the range of behavioral parameters that may affect HP performance are drawn, and the important influencing factors are analyzed, which is innovative. It is suggested that the authors consider supplementing the statistical results of the study cases to make the article more convincing.

2. In the introduction, it is suggested that the content related to the working principle and performance of HP should be briefly introduced, and supplement the content related to the occupant behavior.

3. It is suggested to increase the font size of Figure 1 and Figure 3, and add the legend and its meaning.

4. In the second chapter, it is recommended to briefly explain the research samples and surveys, focusing on the analysis of the survey results; appropriately reduce the content of research methods and basic theory introduction, focusing on how this article is applied.

5. There is no dotted arrow in Figure 4, which is not consistent with the description in the text; line 431 divides occupant behavior into four categories, but only three are introduced below.

Author Response

We would like to kindly thank you for your thoughtful and thorough review of the manuscript. We agree with the comments and have revised the manuscript according to the suggestions provided. Any changes/additions in the revised manuscript are highlighted using track changes. Please also see attached for our detailed responses to your comments.

Author Response File: Author Response.pdf

Reviewer 4 Report

The paper is well written und well structured. The topic is very contemporary and shows important aspects for the necessary and increased use of heat pumps. It is also well presented how the results are to be interpreted. Method is well explained.

The formatting needs to be improved, chapter headings, tables and graphics are partly not well placed and illegible.

The specification of a very low sink temperature in relation to legionella prevention could be misleading - significantly lower temperatures can be used for space heating, which is opposed by the hygiene pact of the drinking water. 

The role of crafts, e.g. availability and training, has an influence; if necessary, present this more prominently.

If possible tables should not be splitted.

The chapter heading 2.1 seems to have moved

Figure 3 looks blurred and illegible. Furthermore, it is not easy to understand what it represents. The presentation should be improved. Is there a literature source? If so, include it in the caption.

The chapter heading 3.2 seems to have moved

Unfortunately, the added value for the necessary heat transition or contribution of decarbonisation for heating sector is not made clear. This should be emphasised more clearly.

Examples of the important implications for policy makers, installers and manufacturers of HP systems and their users should be given even if they are case study specific.

An outlook is lacking, where exactly would need to be addressed. What was still missing?

Author Response

We would like to kindly thank you for your thoughtful and thorough review of the manuscript. We agree with the comments and have revised the manuscript according to the suggestions provided. Any changes/additions in the revised manuscript are highlighted using track changes. Please also see attached for our detailed responses to your comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Please accept. 

Reviewer 3 Report

As it is.