Standard of living refers to the quality, and quantity, of goods and services made available to an individual for his/her consumption. This definition is a general one and is easily understood.
To improve one's standard of living, in accordance with this definition, one needs to be provided with a better quality goods & services , such as advanced electronics and gadgets, or quantity, such as producing more self-care product for consumption.
So how does this conflict with his/her environmental concerns? In order to improve standard of living, there is a few trade offs. To produce more quantity of goods & services, more resources have to be used. This might lead to excessive usage, wastage & depletion of natural resources. For example, to provide more fuel to the society, companies have to extract more & more of fossil fuel. Sustainable usage of natural resources might be a concern, since some types of resources are unrenewable e. g oil & gas.
Production of higher quality products requires advanced state of technology. In the meantime, the use of some technologies aren't exactly environmental friendly i. e it may create pollution. For example, decades ago, manufacturing shirts using traditional methods might not yield consistent results thus the invention of machine helps with increasing the quality, however, results in noise and air pollution. Another example, using air-conditioning instead of hand fan is more effective in coping with hot weather, but greenhouse gas is emitted.
This shows the conflict between environmental concern and the desire to improve standard of living in general.
Hope this helps!