As a lot of posters don't seem to know how the Dáil functions, I have written an explanation - sorry for the length.
1) In modern parliaments committees meet simultaneously with plenary sessions (plenary sessions are the full parliamentary session taking place in the chamber). At many times 50 TDs+ may be attending committee meetings while the plenary is on. They are in the committee rooms. Members of the public can go in there at any stage to watch them.
2) All TDs (like parliaments worldwide) have video links on TV screens in their office. So they can, and do, sit in their offices and watch it from there. They can also watch the Seanad, the House of Commons, the House of Lords, the European Parliament or many other parliaments, or watch Sky News, BBC World, CNN or whatever, and so follow international events. Members had to sit in the chamber of a parliament in the 19th century to follow debates. They haven't to any more, so most don't. Only a small number of members of a parliament sit in the plenary chamber, usually those directly involved at that moment in the debate (ie, those scheduled to speak in the next few minutes). The rest follow it from their offices, and come down for their speaking slot.
3) Parliamentary chambers in general are not particularly good places to follow debates. The US congress spent millions trying to improve the acoustics of the Senate and Representatives, and ended up having to remove the original ceilings and put in special ones. The Dáil because of its size has particularly poor acoustics. Someone up in the office listening on the monitor will hear things far better than the sod sitting in the chamber. So most TDs prefer to follow debates on the monitor than struggle to hear in a very large cavernous chamber. The Dáil chamber also has another problem. Because of its size it is very hard to heat. It has an old boiler system which depending on how it is on, either turns the chamber into a fridge or an oven. For that reason too people tend to avoid it if they can and work from their offices. Their offices at least aren't an oven or a fridge, though the fact that the damn Greens blocked an attempt to put in air conditioning means that people largely rely on windows that automatically open and shut for no logical reason (ie, open when it is snowing or at 8pm on a cold night, stay shut in a heatwave or at midday) and when opening make a sound like a chainsaw. (If you ever are onto your TD on the phone and you hear the sound of a chainsaw it is those damned windows opening again. They can be over-ridden, but only standing like an ejjit for minutes pressing an override button and waiting for it to do something. All sides curse the Greens for their damn insistence on those 'environmentally friendly' bloody windows.)
4) In the Dáil unfortunately the rules of debate are crazily restrictive and governments won't change it. In Westminster, ministers "give way" to allow someone to make a point so there is a cut and thrust. In the Dáil it all consists of people standing up giving a ten minute speech, then been replaced by someone else giving a ten minute speech, then another, and another, with no cut and thrust.
5) For every person who complains that there are not enough TDs in the chamber, another will complain if their TD is in the chamber, ringing up to say things like "what the fukk are you doing sitting around on your arse all day. Why don't you do something useful?'
The idea that TDs are off mitching or in the bar or something when they are not in the chamber is fanciful. There is no sense in sitting around for hours on end in a stuffy or freezing chamber where you cannot hear the debate properly, unable to contribute until your time comes hours later, when you might as well be in your office able to listen to the debate clearly, deal with paper work and be available if someone calls - even if you are constantly been interrupted by the 'chainsaw' windows opening and closing as they feel like it. When it came to the debate on the economy today, BTW, people could follow it in their offices while keep an eye on the bond markets, or read up on what was making international news, or even reading this site (and yes, some do!).
BTW, in case you wonder why the Dáil is empty while the Commons looks crowded, that is an optical illusion. The Dáil chamber is physically very spread out and has more seats in it than are needed. So even if the house is one-quarter full it looks as if less than 10% full. The Commons is a tiny chamber - really really tiny when you see it in real life. Everyone gets a shock when they see it - about the size of your average rectangular bungalow, with seats for only 450 though there are 650 MPs. So even when only 10% of its members are there it looks at least a quarter full. When full MPs sit on the steps, behind the speaker's chair and in an overflow gallery beside the public gallery. It also has fantastic acoustics, unlike the Dáil.
If it was up to me, I would make the Dáil chamber smaller - I'd turn the overflow seats in the front into the government and opposition benches, to create a more intimate relationship like in Westminster, remove the back row of seats, and put in proper acoustics.
BTW - one other difference with Westminster. In Westminster you have to "get the speaker's eye" to get called - hence the sight if MPs bobbing up and down looking to be invited to speak. In the Dáil the party whips draw up a list. They allocate time. So you get told you are speaking at, say, 4.30 to 4.40. So you follow the debate in your office until 4.25, head down to the chamber (anything from 30 seconds to 5 minutes depending on where your office is), get called off the list by the Ceann Comhairle who has received a list from the whips, then when you are finished at 4.40 head back to your office to follow the debate.
So if there are four or five TDs in the chamber, that is usually
- one government minister (often the sponsoring minister. So if it is Finance debate, the Finance Minister or junior is often there)
- one representative from Fine Gael and one from Labour.
- Occasionally one representative from Sinn Féin
- The speaker on his or her feet
- The person due to speak next.
Anyway, guys, that is how the place works. Come in and see it sometime. Your TD can get you in. The Dáil chamber is located in the nineteenth century extension to Leinster House - between the original Leinster House and the National Museum, the Seanad is on the old ballroom of the original 18th century Leinster House (two windows on the left of the Kildare Street side on the first floor) while the committees meet in Floor 0 (basement) of LH2000 - the millennium wing between Leinster House and the National Library.