Multifamily Housing Energy Efficiency Improvement Act of 2014 - Requires the Department of Housing and Urban Development (HUD) to analyze and report on the relationship between energy savings improvements to homes and buildings, utility and energy expenses, and mortgage performance. Directs HUD to make the results of the analysis publicly available.

Requires HUD and the Federal Housing Finance Agency to evaluate departmental procedures and policies to assess if they accurately reflect the energy expenses and benefits of energy savings improvements for homeowners and building owners.

Amends the National Housing Act to revise provisions concerning mortgage insurance by establishing a green refinancing program for multifamily housing projects to increase the amount of mortgage loans that may be insured to finance the cost of residential energy conservation measures.

Requires HUD to carry out a Multifamily Housing Energy Innovation Plan to make grants to establish or expand an energy savings plan that will result in at least a 20% reduction in the energy, water, or gas consumption of multifamily housing.

Authorizes HUD to waive during the next five years any requirement regarding the eligibility of multifamily properties for an existing risk-sharing agreement entered into under multifamily mortgage credit programs, if the waiver facilitates the adoption of energy or water conservation measures in the properties.