"It's a very, very lonely place," Senator Ryan told an audience at the Institute for Government in London, where he also gave a speech on representation in the Senate.

The design of the building has influenced politics, Senator Ryan said, and although it is a marked improvement on Old Parliament House, the lack of interaction isn't necessarily a good thing.

"If you're having a bad day in Parliament, you can be away from home, you can be isolated in your office, you can be being beaten up for something that went wrong by the media, it can be a very, very lonely place."

Senator Ryan said he wasn't complaining about the "majestic" building, and pointed out that Old Parliament House was no longer fit for purpose when the move was made in 1988, but the design served to separate MPs from each other, and ministers from backbenchers.

Members and senators with their own offices with individual bathrooms and kitchenettes were less likely to have "spontaneous interaction" with others, he said.

"If you come to our Parliament House on the busiest day of the year, which is our budget day, you can still walk down a corridor and not see someone. It is a cavernous building."

Backbenchers are less likely to visit the offices of ministers, Senator Ryan said, which can lead to unrest escalating faster than they otherwise would.

"As a minister I can tell you, compared to when I worked there in the '90s, backbenchers didn't just walk into the ministerial wing and pop in and see ministers as much as they used to, personally I think that's one of the things that's happened in the last 15 years, ministries have got more distant from their caucus colleagues.

"I think that has led to problems getting bigger before they get resolved, which could explain some of the internal party tensions."

Senator Ryan also praised the role and diversity of voices of the Senate crossbench, describing how 8 per cent of Australians vote for the major parties in the House of Representatives and vote for minor parties in the upper house.

"The Senate guarantees the consideration of additional voices in the legislative process as, more often than not, the support of either the opposition or minor parties is necessary," he said.

"In an era where lower political party identification amongst voters appears to be a long term trend, this is important in maintaining democratic legitimacy and consent, and limiting the risk of interests and experiences not being heard, leading to further frustration and disenchantment with governing and democracy itself."

For just eight of the last 50 years the government of the day has had a majority in the Senate, Senator Ryan said, meaning even election promises and the annual budget can be contested in the house of review - a "defining feature of Australian politics".

"Their passage is in no way guaranteed."

Senator Ryan also slapped down former deputy prime minister Barnaby Joyce's proposal to change Senate representation to increase the number of regional senators.

"The current Senate is actually very reflective of the national vote despite the differences in state populations.

But this proposal would destroy that."

"The consequences would be the elimination of most minority voices and parties, as well as dramatically reducing the value of urban voters in the election of Senators."