Morten Gjerde

The potential benefits of retrofitting thermal mass into New Zealand houses

This article reports on a study undertaken to investigate the effectiveness of thermal mass to moderate indoor air temperatures and to reduce energy demand when it is introduced into existing timber frame residential buildings. The research investigated characteristics of the existing New Zealand housing stock and how energy is used in those dwellings. Six different house typologies were defined and computer models created. Different combinations of thermal mass retrofits were assigned to each house type with variations also involving heat pumps. In all, the investigation produced 72 different scenarios, each of which was modelled for thermal performance using IES VE software. General trends indicate that thermal mass retrofits are more effective in older houses, with more recent dwellings generating little improvement on average annual indoor temperatures. This is most likely a consequence of the higher insulation levels required in the newer houses as well as lower infiltration rates. In a sense, these newer houses start from a higher performance level and the introduced thermal mass provides relatively smaller improvements. The research concludes that, while thermal mass is an integral part of passive solar design, insulation is much more important, particularly in houses where smaller areas of glazing limit the extent to which the sun can charge the mass. A useful outcome of the project is a set of cases that can help inform residential owners about different passive retrofit options and the associated benefits to costs.

Generating Consensus: A Framework for Fictional Inquiry in Participatory City Gaming

Contemporary digital urban design games or ‘city games’ can function as a constructive instrument for exploration and discourse, serving as an essential interface between abstract decision-making processes and real world development decisions. Research suggests that city games are useful for engaging stakeholders, allowing them to explore a range of ideas. However when dealing with marginalized communities with low levels of cognitive consensus, one difficulty is that conventional city game approaches tend to engage pragmatic problems set in realistic contexts, rather than providing scope for discussion of the “soft city” or intangible aspects of a community. To address this problem, this paper proposes a new constructive gaming framework that incorporates Fictional Inquiry along with a “perceptual bridge” to help players contextualise a fictional proposition within their perception of real world problems. Fictional Inquiry differs from traditional participatory design practice as it temporarily changes or bypasses existing socio-cultural structures. The aim is to help marginalised communities learn to make effective decisions about intangible issues, and then to transform those choices into desired actions and outcomes. This paper illustrates the advantages of a perceptual bridge through the design of a new participatory design game the author calls “Maslow’s Palace”. This new conceptualised framework may be used as a catalyst to enable stakeholders in marginalised communities to foster a common vision through fictional inquiry as a prefix to pragmatic community design processes where consensus is required.

Evaluation of fluid pressures applied to the building envelope during maintenance

Maintenance of the building envelope is required by the New Zealand Building Code. Although normal maintenance is not specifically defined, the code does limit the forces that might be applied to a building as defined in AS/NZS 1170:2002, Structural Design Actions. This article reports on research that quantifies and contextualizes the pressures that are applied to the building envelope during washing. The study includes evaluation of pressures exerted by the garden hose as well as small and medium-sized water blasters that are typically used by home-owners. A prototype test rig was designed and built to measure the forces applied by the water to flat surfaces, intersections and internal corners. Measurements were recorded at various distances from the test rig. Directly relating the recorded data to the water penetration limit state, the building envelopes design limit, identifies cleaning processes that are inappropriate and breach the NZ Building Act. The results identified that some commonly performed cleaning processes may subject a buildings exterior to forces significantly greater than they are tested or designed to withstand. Significantly, the greatest forces a buildings envelope (its elements and details) will experience throughout its life are those applied during the cleaning of the building.