The average annual carbon footprints in the different subgroups (kg CO2e/a)

Table 2. The average annual carbon footprints in the different subgroups (kg CO2e/a). Abstract The relationship between urban form and greenhouse gas (GHG) emissions has been studied extensively during the last two decades. The prevailing paradigm arising from these studies is that a dense or compact urban form would best enable low-carbon living. However, the vast majority of these studies have actually concentrated on transportation and/or housing energy, whereas a growing number of studies argue that the GHG implications of other consumption should be taken into account and the relationships evaluated. With this two-part study of four different area types in Finland we illustrate the importance of including all the consumption activities into the GHG assessment. Furthermore, we add to the discussion the idea that consumption choices, or lifestyles, and the resulting GHGs are not just a product of the values of individuals but actually tied to the form of the surrounding urbanization: that is, lifestyles are situated. In part I (Heinonen et al 2013 Environ. Res. Lett. 8 025003) we looked into this situation in Finland, showing how the residents of the most urbanized areas bring about the highest GHG emissions due to their higher consumption volumes and the economies-of-scale advantages in the less urbanized areas. In part II here, we concentrate only on the middle-income segment and look for differences in the lifestyles when the budget constraints are equal. Here we also add the variables housing type and motorization into the assessment. The same time-use and private expenditure data as in part I and the same GHG assessment method are used here to maintain high transparency and comparability between the two parts. The results of the study imply that larger family sizes and economies-of-scale effects in the less dense areas offset the advantages of more dense living when the emissions are assessed on per capita basis. Also, at equal income levels the carbon footprints vary surprisingly little due to complementary effects of the majority of low-carbon lifestyle choices. Motorization was still found to increase the emissions, but a similar pattern regarding housing type was not found.

表2. 不同亚组的年均碳足迹（千克二氧化碳当量/年，kg CO₂e/a）。
摘要 近二十年来，学界已围绕城市形态与温室气体（GHG）排放之间的关联展开了大量研究。此类研究衍生出的主流范式认为，高密度或紧凑型城市形态最有助于实现低碳生活。然而，绝大多数此类研究实际上仅聚焦于交通及/或住宅能源领域，而越来越多的研究指出，应当将其他消费活动的温室气体影响纳入考量，并重新评估二者间的关联。
本研究以芬兰四类不同区域为对象，分为两个部分展开，旨在阐明将所有消费活动纳入温室气体排放评估的重要性。此外，本研究还补充了一项讨论视角：消费选择（或生活方式）及其产生的温室气体，并非仅由个体价值观决定，实则与周边城市化形态紧密相关——换言之，生活方式具有情境依赖性。
在第一部分（Heinonen等人，2013，《环境研究快报》(Environ. Res. Lett.) 8 025003）中，我们针对芬兰的这一议题展开了研究，结果表明：城市化程度最高的区域居民因消费规模更大，而欠发达区域存在规模经济优势，因此其温室气体排放量也最高。
在本文的第二部分中，我们仅聚焦于中等收入群体，旨在探究预算约束一致时不同生活方式间的差异。本次研究还将住宅类型与机动化水平两类变量纳入评估体系。本部分沿用了第一部分所用的时间使用与私人支出数据，以及相同的温室气体评估方法，以确保两部分研究具备高度的透明度与可比性。
研究结果显示，若以人均为基准核算排放量，则低密度区域更大的家庭规模与规模经济效应，会抵消高密度居住模式的减排优势。此外，在收入水平一致的情况下，多数低碳生活方式选择的互补效应使得碳足迹差异出乎意料地微小。研究还发现，机动化水平仍会推高排放，但未观察到住宅类型与此相关的类似规律。