Buckminster Fuller used to ask architects 'how much does your building weigh?' It's still a good question, but it's not one heard often down at the planning department, where the overriding obsession is always 'how tall is your building?'. Other questions that you might think more interesting, about whether buildings are useful, durable, beautiful etc., languish way down the list of priorities.
One consequence of this strange obsession is that new buildings are often expected to 'step down to respect the scale of the neighbouring buildings'. Since in most cities that I can think of, not all buildings are the same height, it might be thought inevitable for some buildings to be taller than their neighbours. But this apparently self evident proposition is not accepted as readily as you might think, and all over London you can see recent buildings where chunks have been lopped off somewhere between the original idea and the granting of planning consent.
Here in Wigmore Street, in the days before we had planning departments, a thoughtful architect noticed that his new building would be taller than its neighbour and decided to make it step up, not down, at the party wall, by making something special of the chimneystack. Most new buildings today are a lot cruder than this, and architects get fewer fun elements like chimneystacks to play with than they used to - but you have to wonder whether our townscape might be better served by planners insisting on architects having a bit more more fun, rather than 'stepping down'.
Here is a warning about 'stepping down' from the CABE / EH guidance 'Building in Context':
'...when a tall building meets its lower neighbour at more or less the same height and then gets higher in steps as it moves away along the facade. Unless the change in height arises out of the requirements of the brief, this can produce a lop-sided appearance in the new building and merely emphasises the difference in height between the two. Unless it is done with great finesse it does the older building no favours at all...'