The House Value indicates how much the Sim's/player's total assets are worth. This total includes the Item Value and Clothing Value. The House Value total is indicated on the lower left side of the playing screen, under the avatar's profile image and traits.
House Value Basics
Purchasable items for the home add 'Item Value' that is part of the overall House Value total. These items are indicated by a house with a Simoleon image in the buy menus under Shop and Build. Objects, doors, windows, and rooms all have House Value points associated with them, but tiles and wallpaper options do not (although they still cost Simoleons or SimCash).
In the August 22, 2012 update, clothes were given value that could be added to the overall House Value.
The cost and House Value points of a object are usually not equal: Simoleons items usually have a house value of 1/2 the cost of the item, Social Points items usually have double the house value to the cost of the item, and SimCash items have a roughly equivalent house value total to the conversation rate of the SimCash to Simoleons (Currently 15 -> 1800 ).
It is important to note that objects in inventory still add to the overall House Value. This may be part of the reason why there is an item limit for each player of 500 objects and house building materials.
Purpose of House Value
A player's House Value Level determines where they will see themselves in the scrollable queue of neighboring Sims/players. Four clickable images of Facebook friends and their Sims appear in this horizontal list at the bottom of the playing screen, with a "Add Neighbor" option with a Plumbob image in the middle. The Facebook friend with the highest House Value Level appears at the far left, and Bella always appears on the far right (not in the scrollable list).
Certain House Value levels allow Sims to unlock more space on their lot.
Visually, the only change will be the street in front of your house where you place Driving Skill items like cars, scooters, or special items. Higher value homes will have shrubs and better paving along this street.
House Value Levels26K, at Level 1. Each House Value level has a number, value, name, and street name associated with it.
While house value does not automatically lead to an increase in lot size, increasing house value will unlock plots around your lot which you can then buy to expand your lot size. See the Lot Expansion page for more info about house value and expanding your lot.
Levels indicated with a star (*) will earn you an achievement.
Some information provided by: The Sims Social on The Sims Wikia.