Sarah Ward, Iowa State University

The Tier House

The Tier House is designed as a single-family residence suited for the Midwestern region of the United States, notable for both its hot summers and its extremely cold winters.  Its name comes from both its form and function.  The three tiers of building design: basic building design, passive systems, and active systems, are implemented in order to provide a beautiful, simple, and attainable model that can be applied to many neighborhoods.

Tier 1: Basic Building Design

The design takes advantage of simple geometry.  By maintaining a rectangular footprint, the surface-to-volume ratio remains low, which helps conserve heat in winter. The East and West sides of the house have high windows, which are shaded from direct light by the roof overhang.  All exterior walls are heavily insulated and have rain screen cladding systems that can be customized to suit the aesthetic desires of the homeowner.

Tier 2: Passive Systems

Throughout the building envelope, the thick walls are used for thermal mass.  An entryway the entire length of the northern exterior wall is also incorporated into the design as a weather shield.  The entryway, or vestibule, allows for an interior curtain wall, which lets light enter into the public spaces of the house (by way of upper exterior windows), while keeping out the cold.  The southern living spaces also benefit from high thermal mass and low infiltration provided by the wall adjacent to the garage.  In addition to the thermal mass aiding in summer by retaining cold air, the high roof also allows heat to rise.  This raises the amount of the day when rooms can have an adequate thermal comfort level without heavy use of mechanical systems.  The tall roof also provides opportunity to create ceiling clouds of different heights.  This allows for control of the intimacy or grandness of a space.  It also creates beautiful reveals of materials and lighting conditions.

Tier 3: Active Systems

A fireplace is located on the North side of the house between the two major public spaces.  Its location is not only good for thermal comfort, but also defines a social gathering space and focal point of the house. 

The roof is tilted upwards towards the North side of the house.  The slope to the South has the opportunity to collect rainwater for toilet flushing at the top most tier, and the lower roof section can collect rainwater for watering plants.  The low Southern elevation and high Northern elevation is also ideal for solar harvesting.­­­­­