Intent-based networking (IBN) aims at automatically driving network configurations and operations to fulfil high-level intents specified by infrastructure providers and application operators. Deploying Virtual Network Function (VNF) chains onto the available network resources is a way to model and fulfil intents. Focussing on the Cloud-Edge continuum, this article describes and compares a mathematical programming and a declarative heuristic methodology to solve the problem of placing VNF chains to fulfil multiple intents in IBN settings. Taking the infrastructure operators' viewpoint, our approach aims at balancing the trade-off between environmental sustainability and profit. We release an open-source prototype of the proposed methodology and assess its scalability and functioning via simulation over lifelike data.