So-called corporate authors need to be protected by a pair of curly braces to avoid that BibTeX or Biber tries to parse the name as the name of a person with family and given names. See Using a 'corporate author' in the "author" field of a bibliographic entry (spelling out the name in full). So you need
author = {{Bundesministerium für Umwelt, Naturschutz und nukleare Sicherheit (BMU)}},
biblatex-ieee applies sentence casing to some titles and so "Klimaschutzplan 2050. Klimaschutzpolitische Grundsätze und Ziele der Bundesregierung" will be converted to "Klimaschutzplan 2050. klimaschutzpolitische grundsätze und ziele der bundesregierung". The English rules of sentence case that biblatex applies here make no sense of a German text, so the best we can do is tell biblatex that this is a German title that should not need any case changes. This is done by adding
langid = {ngerman},
to the entry. In case you do have an English title where sentence casing should apply, but you need to protect a few proper names or acronyms from case change, you will, however, need curly braces again. See BibTeX loses capitals when creating .bbl file.
Finally, note that date = {11.2016}, is the wrong input format for date-like fields. biblatex expects date input in YYYY-MM-DD format of ISO 8601. So
date = {2016-11},
would be the expected input.
Putting this all together
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[backend=bibtex, style=ieee,doi=false,isbn=false,url=false]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@misc{bmu,
author = {{Bundesministerium für Umwelt, Naturschutz und nukleare Sicherheit (BMU)}},
title = {Klimaschutzplan 2050},
subtitle = {Klimaschutzpolitische Grundsätze und Ziele der Bundesregierung},
date = {2016-11},
langid = {ngerman},
}
\end{filecontents}
\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}
\begin{document}
\cite{sigfridsson,bmu}
\printbibliography
\end{document}

Note that BibTeX is considered a legacy backend now and that only Biber supports all of biblatex's features. So you may want to consider switching from backend=bibtex to backend=biber. See Biblatex with Biber: Configuring my editor to avoid undefined citations for help on getting your editor to run Biber instead of BibTeX for you. bibtex vs. biber and biblatex vs. natbib has a bit of background, so does Question mark or bold citation key instead of citation number.