What is a "high efficiency"apartment?

This may be a dumb question - but this is a new phrase for me. What exactly is a high efficiency apartment?


I thought it just meant efficiency of $rent per sqaure foot. But then I saw a listing that said 'efficiency of 91.3%' which all seems very scientifically calculated. Can anyone shed any light on this for me?

It depends what the 91.3% refers to.


The usable area of the premises is the net area and usually will also include all structural columns and the external faces of the exterior walls. The efficiency of a net area will usually be 90-100%.


The lettable area is the net area plus a proportion of the communal areas such as the lift lobby, corridors, clubhouse, etc. The efficiency of a lettable area typically ranges from 70% to 90%.


The gross area is similar to the lettable area and will also include a pro-rata proportion, of various elements of the common areas. The efficiency of gross areas is generally between 60% and 80%.


Check which your agent is referring to.

Thanks v much everyone - although I'm still a little confused. The percentage refers to the amount of the apartment that is useable (where 'usesable' is defined by some agreed standard metric) - is that correct? And then, depending on whether we're talking about useable area / lettable area / gross area, the percentage will than obviously change.

Moved to property chat

This is from a government paper.


2.2 In residential property development in Hong Kong, the efficiency ratio (ER) for a residential site is generally recognised as the ratio between the saleable area (SA) and the gross floor area (GFA) and is expressed as a percentage. According to the Code of Measuring Practice issued by the Hong Kong Institute of Surveyors, the SA of a unit comprises the floor area exclusively allocated to that unit, but excludes the common areas such as staircases, lift shafts, lobbies and common corridors.


2.3 The GFA of a building, on the other hand, is calculated in accordance with the statutory definitions provided in the Building (Planning) Regulations and the Practice Notes for Authorised Persons. According to the Code of Measuring Practice, the GFA is defined as the area contained within the external walls of a building measured at each floor together with the area of each balcony.


2.4 For any given site, the allowable development ratio (or plot ratio) is fixed, which in turn determines the maximum GFA that can be built. It follows that the higher the ER, the higher will be the SA relative to the GFA. In the private sector, developers try to maximise the ER of their developments, because a development with high ER usually provides more SA, which is for the exclusive use of the occupants. Residential developments with higher SA are usually more marketable than those with low SA.




So as you can see, the Gross Floor Area really isn't much of a help in knowing how much space you'll actually have to use for yourself... although that is the favourite figure for developers to quote.


Sound knowledgable by asking the agent if the efficiency ratio of 91.3% is calculated according the Hong Kong Institute of Surveyors Code of Measuring Practice.

Cheers Claire!

And will do on the sounding knowledgeable front too!

Many thanks.

Well if you ask for all ERs to be quoted according to the Code, you'll be able to compare apples and apples.

Generally in Hong Kong the size of the property which is quoted will include everything which could possibly be called part of "the area". This means that property sizes are quoted as being much bigger than would be the case in other countries eg in Australia only the net livable area is given. Thus the concept of "usable floor area" which it seems has been brought in to bring some reality to advertisements. Carpark space, the space inside the lift etc are not really useful when you are working out if you can have a house guest or not!