As you come up the ramps and onto the ring road, you get sweeping views of distant hills and nearby Canberra city to one side and the green sloping grass and majestic lines of Romaldo Guirgola'sarchitectural creation to the other. There is a sense of breathing room; a feeling you are in a special place.

One part of my brain may be worrying about securing a park and whether I left my lunch on the kitchen bench. But another part is enjoying a small, but solemn moment of peace.

Parliament House is one of the most beautiful and thoughtful public buildings in Australia. It is full of symbolism, from the green and red tones that mimic the Westminster tradition and the Australian bush, to the careful use of local materials and placement of the building in the surrounding landscape.

The central part of Parliament House is built right into Capital Hill. As Guirgola explained: "The building should nest with the hill, symbolically rise out of the Australian landscape, as true democracy rises from the state of things." The front forecourt is similarly meaningful, with the Parliamentary Education Office describing it as a "large open space ... framed by two walls that appear to be outstretched as if in a gesture of welcome".

Since Parliament House was opened by the Queen in 1988, there have been a number of changes to the precinct in the name of improved security. People haven't been able to walk over the top of it since 2005, various bollards have been added, access to the ministerial wing has been restricted and police now guard the area with serious-looking guns.

But while these changes are significant, they have nothing on the 2.6metre-high steel fence that is under construction around the building. Suffice to say, my morning drive around Parliament House is steadily becoming less glorious.

Trees have been felled, lawns ripped up, trenches dug and temporary fences have lined the grassy slopes. As of Tuesday, a crane began to manipulate chunks of the permanent fence across the lawns. This is all in aid of a security upgrade that has its origins in a review, ordered by the Speaker of the House and President of the Senate in 2014, with input from ASIO, the Attorney-General's Department and the Australian Federal Police.

But what makes this hulking fence – that seems to go against the spirit as well as the aesthetic of Parliament House – so offensive is the lack of proper public explanation for it. The fence was ticked off by Parliament at the end of last year, but so far, its precise cost and design remain a secret. MPs have been offered confidential briefings but next-to-nothing has been shared with the public on the grounds of national security.

Architect Hal Guida, one of the moral rights holders of the late Guirgola, helped to prepare the design. But again, there has been no public consultation.

Official opposition to the fence has been muted at best. When the changes came before Parliament only nine senators – independent Derryn Hinch and the Greens – opposed the plan in the upper house. The Australian Institute of Architects, while raising initial concerns, was given a confidential briefing and accepted there was nothing it could do to stop the construction. In June, the National Capital Authority (the governmental guru on all things Canberra) told a parliamentary committee the fence was "not ideal" but conceded, it was needed for security reasons.

It is easy to understand that those responsible for security at Parliament House want to do everything in their power to keep the building and the people in it safe. On top of all the very important politicians who work here, there are another 3500 building occupants and a further one million visitors a year, including 100,000 school kids.

And there is logic to the argument that we don't get to know everything our security agencies know because we need to keep this information from people who want to hurt us. It's also noted – with much happiness – that access to the front entrance is not being changed.

But when we are talking about a building that was designed as a place that would welcome the public, that was for the public, it's not good enough to provide so little explanation for such a profound change. When we're not given any information, we imagine the very worst, for the worst reasons.

So as the fence work continues, diminishing the grace of this beautiful building, it's very difficult to keep calm and carry on.

Judith Ireland is a Fairfax senior writer who works at Parliament House.