Irish people like BIG houses. The imperial measurement system is still in use because people like to think of space in 'thousands'... 2500, 2700, 3000...square feet please. I need a room for my kids, a room for the boots, a walk in hot press, a room for tins and bags of flour, 5 toilets, 3 spare bedrooms 'think of christmas'... Ok, I'm exaggerating ...or am I?
For me, its not about how much space, its about the quality of that space and how it meets the needs of the person living there. Imagine two kitchen's, one is large, north facing, window over the sink, large kitchen table somewhere in the room,... now think about a small bright kitchen, south-west facing, light streaming in a glass door which opens to an abundant luscious garden. Designing space is about imagining how that space will be when it is finished. Will it have light, how does it connect to the rest of the house and to the outdoors. How will you feel when you are in that space. The first kitchen I described feels cold, dark, unwelcoming while the second space feels inviting, relaxing and connected.
So when you are thinking about extending or building a new house, yes, do write down a list of what you need but more importantly think about how you want to feel in your home. If you like clean minimalist spaces, then you need to consider storage, where are you going to hide everything away? If you like a quirky lived in look, then what about lining walls with shelves or adding quirky nooks. What atmosphere do you want your home to have? Think less about how much space you need, but how you want to use that space and most importantly how you feel in that space.