I have a pretty old house, around 100 years, old enough that no-one really knows how old it is. It's a single level weatherboard house, 120 odd square meters. The front of the house has the living area, three bedrooms, bathroom, and lounge. A single standard door leads through to a big open plan kitchen/dining, with an office and laundry off it. The house has very good insulation in the ceiling, walls, and under the floor, and retrofit double glazed windows in the living area of the house. It resists ambient air temp pretty well, but the big windows let the sun's heat in. In winter it's pretty good, if it's 5 degrees outside it'll drop from 20 to 18 overnight with no heating on. Problem is the same thing happens in summer.
The bedroom/lounge area gets morning and early afternoon sun, but with curtains we can block it out pretty easily. It gets up to around 22-23 degrees when ambient is around 28. Opening the windows doesn't help much, there's virtually no breeze, and even if there is not much goes through the house.
The kitchen, dining and office areas have dark blinds and lots of windows. It can get up to 35 degrees or higher on a sunny day. There's a bit of a catch 22, if you open the windows you have to open the blinds which lets the sun in. Keep them closed and the heat gets in anyway. I'll address that with light color window coverings one day, but you have to be careful in kitchens.
The house has an air conditioner/heat pump in both areas, a big 10KW unit in the living area, a smaller but still decent 7KW unit in the kitchen. To get to our bedroom the cool air (or in winter, heated air) has to go around a 180 degree turn via the hallway, we sometimes use a pedastool fan to help with that. The air conditioner in the kitchen pushes air down the same hallway, which means only one 90 degree turn. Getting the air temperature down when they're on is pretty easy, it only takes 20 minutes. What I find though is even if we get the air down to say 18 degrees with the air conditioners on for an hour it soon heats up, I presume because the carpet, the walls, the tons of wood that make up the house are still at 22+ degrees.
The house also has a cheap DVS unit. Outlets go into the kitchen and the hallway, though I've set it to only operate when the roof cavity's below 22 degrees in summer. I also have it turn off at night because the noise bothers me, though I could probably live with it, but there's not much point because the outlet isn't near the master bedroom and wouldn't help air movement much.
If it gets super hot we can just move into our main spare room, right in front of the big heat pump, which can make any temperature we like within about 5 minutes. We like our room though.
Does anyone have any thoughts on cooling or ventilation? It's rare to need it in Wellington, so I wouldn't compromise the winter insulation for the few days that it'd be helpful in summer. I guess we need to either add some kind of ventilation, some air movement (not too much as it'd be noisy or wake us during the night), cool the air, or stop it getting hot in the first place.