Controlled cooking tests comparing the financial, energy and time costs of different food and stove combinations in Nairobi, Kenya

Review
1.) Reasons for combining fuels especially with charcoal, it is the ease of staring up the source where the charcoal source is referred at the evening and in the morning people want a quick start-up and off source of cooking energy.

2.) The major difference between EPC and other forms of cooking comes clearly at any cooking that goes beyond steam generation, where the EPC has an advantage than any other cooking system due - steam retention but up to just boiling point the other cooking techniques beat the EPC, this is seen below,

a.) In fig 10, for water boiling Induction cooker uses least energy followed by Infra-red and lastly EPC. For Sukuma wiki the IN and EPC are almost equal followed by IR. For rice EPC beats IN and IR due to steam production and containment but for ugali which is open cooking the IN leads followed by EPC and Lastly IR.

b.) In fig 11, The IN uses least time, followed by IR and lastly EPC in non steam containment cooking tests water boiling, sukuma-wiki and ugali. For Rice IN leads then EPC and Lastly IR. EPC is faster only in pressure cooking but not in ordinary cooking tests.

c.) What heat production technology is EPC using ? (Resistive element/hot plate, IR, IN) This must be specified to be able to know/explain why there are variations in the time and energy, and why IN and IR are beating it in basic cooking tests among the electrical cooking technologies.

- For the average cooking test results, they are ok, but for the non-steam containments tests, IN and IR of electric are appearing faster and efficient than EPC.

3.) The reason why EPC is efficient in long boiling over other systems?

4.) Some mass for simple cooking tests like boiling water, or cooking beans, or cooking soaked beans, or cooking githeri if possible to be provided, for the purpose of scholarly benchmarking and referencing in further studies. One will know what volume of water, or beans, or soaked beans was used and will have a basis for comparison in terms of energy use, time etc because quantitates are known - Where data is available can be put on the appendix.

Note:
This review refers to round of peer review and may pertain to an earlier version of the document.

Review
Good article on cooking energy and appliances in Nairobi, Kenya.

Suggestions to improve clarity and flow:
1. Title to be refined/redone to reflect all synthesized (merged) Objectives and Results and Conclusions
2. Methodology to be rearranged and numbered to flow/agree with Results
3. Results to be reorganised in line with objectives
4. Inference to Sub-Saharan Africa to be for specific foods

Few Revision required

Note:
This review refers to round of peer review and may pertain to an earlier version of the document.

Review
The article gives a clear account of the challenges faced by residents of Kenyan areas when it comes to cooking cleanly (in terms of fuel choice) and financially (in terms of costs per meal and cooking method. As such it is scope of the journal as it deals with a topic that intersects fuel types and efficiencies and social issues such as costs.

This kind of field work presents a number of challenges in methodology and interpretation. The authors have worked hard on a basic and consistent methodology but have not presented the results of their efforts as well as they might have done. This means the data are difficult to interpret or to make use of.

This could be corrected if a little more clarity could be put into the methodology section and into the figures. If needs be some context and framing amendments might increase the appeal of the work to a wider audience. For example, some material could be supplied that made it clear what other benefits (say health ones) might result from using non-polluting fuels.

The main concern is that although a large number of individual data points have been collected in some parts of the study - such as for fuel prices - the replication in the area of the actual cooking tests is unclear and insufficient account has been taken of the patchy nature of the data on fuels. The number of samples obtained at different locations varies greatly and this needs to be reflected in the way costs are calculated.

The paper states that four portions of food were prepared and also states that three replicates of each cooking method were examined. But nowhere is any indication given on the Figures as to what the number of observations is, for example, for each of the columns in the figures. This is fundamental to publication. For example, if the replication is only three-fold for each cooking method then the study is perhaps of limited value (this does not mean it cannot be published but it is a stumbling block). On the other hand, if there are 12 replicates under consideration - 4 portions prepared 3 times - then the data may be easier to interpret. Whatever is the case it must be clear in the main body of the text and the legends to Figures what the relevant numbers are.

If the value of n is 12 then some statistical analysis would be possible and this would need to be done. If the level of replication is only n=3 then the context and framing of the paper (in the Introduction and Conclusions and/or Limitations) needs some more work as the study must be considered as a more of a pilot study (no harm in that) that might be a preliminary to a more detailed study on the cleanest and most cost-effective cooking methods - the design of any future study would need to be set out at least in outline in this paper.

In either case some attention must be paid to the figures and their legends as it is not clear what the various range and error bars refer to.

If n=3 this is especially important to indicate this clearly because apparent differences in a n=3 study would not necessarily be statistically significant or important if n were, say, 12. It would be important to give reasons why this is a n=3 study in the Introduction or Methodology sections and to discuss the limitations on a n=3 study in the Discussion/Limitations/Conclusion sections so that the reader can make a judgement as to the utility of the work done whilst clearly understanding the context and framing of the study at its outset.

Without the kinds of amendments detailed above the submitted text could not be fully published.

Note:
This review refers to round of peer review and may pertain to an earlier version of the document.