  As the energy footprint generated by software is increasing at an alarming
rate, understanding how to develop energy-efficient applications has become a
necessity. Previous work has introduced catalogs of coding practices, also
known as energy patterns. These patterns are yet limited to Mobile or
third-party libraries. In this study, we focus on the Web domain--a main source
of energy consumption. First, we investigated whether and how Mobile energy
patterns could be ported to this domain and found that 20 patterns could be
ported. Then, we interviewed six expert web developers from different companies
to challenge the ported patterns. Most developers expressed concerns for
antipatterns, specifically with functional antipatterns, and were able to
formulate guidelines to locate these patterns in the source code. Finally, to
quantify the effect of Web energy patterns on energy consumption, we set up an
automated pipeline to evaluate two ported patterns: 'Dynamic Retry Delay' (DRD)
and 'Open Only When Necessary' (OOWN). With this, we found no evidence that the
DRD pattern consumes less energy than its antipattern, while the opposite is
true for OOWN. Data and Material: https://doi.org/10.5281/zenodo.8404487
