In the name of God, the Most Gracious, the Most Merciful
Well Karim, first of all I would like to thank you for asking this important question. To answer your question let's go back in history. Back to the Quran which mentions the following about founding a mosque:
And [there are] those [hypocrites] who took for themselves a mosque for causing harm and disbelief and division among the believers and as a station for whoever had warred against Allah and His Messenger before. And they will surely swear, "We intended only the best." And Allah testifies that indeed they are liars.
Do not stand [for prayer] within it - ever. A mosque founded on righteousness from the first day is more worthy for you to stand in. Within it are men who love to purify themselves; and Allah loves those who purify themselves.
This verse from the Quran couldn't be more illustrative for the contemporary issues Islam is facing now. It also illustrates the foundational power of a mosque in spreading the true message of God: righteousness. Righteousness is universal in this surah and it goes further then basic human rights, it aims to the utmost possible, the best of the best of human behavior. Intending the best is not enough, it should also be practiced. It goes without saying that a righteous mosque shouldn't discriminate between people based on race, gender or any other difference. This means that the design of a mosque should offer equal praying spaces for men and women and both should have equal access to the imam, the library & any other facility the mosque may offer. In the prophet's time women prayed in the same space as the men, but in the back rows. Today, women don't. We sit in different rooms and listen to the imam through a microphone. This is a step backward in righteousness. I believe that with todays technology and creativity we should at least make it possible for the women and the men to be treated as equals: to sit in the same room and to pray on equal foot to our creator. The Quran even commands to never pray in a mosque that isn't founded on righteousness. The implications of this is that the utmost care should be taken in the creation and operation of a mosque. It should be a place of righteousness, purity, safety and unity.
The prophet Muhammad said:
"The (whole) earth has been made a mosque (or a place of prayer) and a means of purification for me, so wherever a man of my ummah may be when the time for prayer comes, let him pray.”
In this sense the whole planet could be seen as a macro-mosque and a mosque could be seen as a micro-planet. What makes a planet a planet is that it is sustainable. In this sense a mosque should be sustainable as well. Things like incorporating solar energy and rain water should be thought about. Also the presence of nature in the form of a garden, and a water fountain are usually part of a mosque and have a cosmic symbolic and practical use. It is also a taste of heaven as it is described in the Quran:
GOD promises the believing men and the believing women gardens with flowing streams, wherein they abide forever, and magnificent mansions in the gardens of Eden. And GOD's blessings and approval are even greater. This is the greatest triumph.
All in all the mosque should be an utopia of beauty and righteousness. It should be a piece of heaven on earth. A safe haven, a purified place where people can purify themselves.
Wishing you a blessed Sabbath,
The Healthy Muslima