http://tex.stackexchange.com/questions/116081/conditional-glossary-style

cond_glos.tex

\documentclass{article}

\usepackage[ansinew]{inputenc}
\usepackage[T1]{fontenc}

\usepackage{etoolbox}
\usepackage{lipsum}
\usepackage{glossaries}
\newglossary[slg]{symbols}{slm}{sbl}{Symbolverzeichnis}
\makeglossaries

\newglossaryentry{ee0}{
type=symbols,
name={\ensuremath{E_{E,0}}},
description={Energieertrag im Jahr 0},
user1=MJ/a,
sort=energie ertrag null
}

\newglossaryentry{erntefaktor}{
type=symbols,
name={\ensuremath{\epsilon}},
description={Erntefaktor. Verhältnis von genutzter Energie zu investierter Energie},
user1=-,
sort=erntefaktor
}

\newglossarystyle{tabx4col}{%
% put the glossary in a longtable environment:
\renewenvironment{theglossary}%
{\vspace{-1.7em} 
\begin{longtable}{@{}p{0.15\textwidth}@{}p{0.1\textwidth}@{}p{0.60\textwidth}@{}p{0.15\textwidth}@{}}}%
{\end{longtable}}%
% Set the table's header:
\renewcommand*{\glossaryheader}{}%
% No heading between groups:
\renewcommand*{\glsgroupheading}[1]{}%
% Main (level 0) entries displayed in a row:
%\ifstrequal{\glsentryuseri{##1}}{-}{

\renewcommand*{\glossaryentryfield}[5]{%
\glstarget{##1}{##2}% Name
& \glsentryuseri{##1}% Units
& ##3% Description
& ##5% Page list
 \\% end of row
}%
%}{
%\renewcommand*{\glossaryentryfield}[5]{%
%\glstarget{##1}{##2}% Name
%&
%& ##3% Description
%& ##5% Page list
 %\\% end of row
%}%
%}
% Sub entries treated the same as level 0 entries:
%\renewcommand*{\glossarysubentryfield}[6]{%
%\glossaryentryfield{##2}{##3}{##5}{##6}}%
%% Nothing between groups:
%\renewcommand*{\glsgroupskip}{}%
}

\begin{document}

\lipsum[1]
\glsaddall
\printglossary[type=symbols,style=tabx4col,title=Symbolverzeichnis] %Print list of symbols
\lipsum[1]

\end{document}