The supply curve of lumber in the U.S. would in effect shift to the left, pushing up the prices we must pay for lumber. Maintenance has declined in part because renters are willing to accept less maintenance in return for lower rents. In addition, it is not profitable for landlords to invest additional money in these apartments, since they cannot expect a competitive return on their investments. We would probably select the renters that were most likely to pay their rent on time and least likely to cause us any problems. We would also want to select those renters who would be willing to spend their own money fixing up the apartments.
Demand is a more precise concept.
It refers to the quantities of a product that consumers are willing and able to purchase at various prices. While my daughter may have been able to purchase the sweatshirt, she was not willing. Podunk may have increased its tuition. The college may have cut back on advertising expenditures, or it may have reduced the number of scholarships available to students. Perhaps a college education does not seem as necessary to success as it did a year ago.