The performance of unheated solar buffer zones (SBZs) or sunspaces in relatively high latitudes' locations has
become increasingly controversial. Conceived as simultaneously saving energy and providing amenity, the
latter characteristic has provided the user with the opportunity and/or aspiration to negate the former - by heating a sunspace during winter either directly, or by opening it up as an extended heated part of the dwelling.
Scotland has been host to passive solar projects promoting the use of small sunspaces where 'opening up' is a
greater risk than directly heating. 'Opening-up' signals a change from 'indirect' to 'direct' solar gain with the
heated volume partially extended. Within this context, this work examines the relevant aspects of a small
sunspace as a passive solar technique by posing three questions from which answers are to be sought.

1. How useful and usable are the sunspaces ?
2. To what extent are occupants' interventions affecting energy saving ?
3. What is the energy 'worth' of the two sunspaces?

The vehicle for this work is the CEC Solar Energy Demonstration Project at Easthall, Glasgow, where 36
thermally sub-standard flats built in the 1960s have been retrofitted with each flat having two sunspaces on
opposite facades to tackle the issue of random orientation, and a common stairwell functioning as a shared
thermal buffer space. The author's close acquaintanceship with a relatively large sample of occupants over a
monitoring period of two years, taken in conjunction with data from questionnaires, interviews, diaries and
personal observations, has enabled a substantive 'cause and effect' analysis.

The findings confirm the likelihood of user intervention negating optimum performance, especially in spring and
autumn, and in association with particular household types and characteristics. Nevertheless, the mean space
heating load was approximately 30% lower than it would have been for the equivalent dwelling adjusted to the
same internal temperature and ventilation rate, but without the front and rear sunspaces; and winter
performance vindicates the role of sunspaces in providing good air quality at a relatively low running cost.

The work sets aside the issue of life-cycle, pay-back analysis since, in general terms, this is dependent firstly on
how much of the cost of sunspaces is written off as necessary floor area or improved amenity, and secondly on
variable costs of a complementary energy-efficient package. However, on the assumption that these factors may
be favourable, the work concludes with broad design recommendations based on the research findings; in
particular recognising the dominance of the 'heat recovery' rather than 'solar' mode of operation of sunspaces.